Shipbucket

Blücher was modernized in 1937 with new anti aircraft guns and combat directors.

And this is her last appearence with radars and more light anti aircraft guns. She fought the Soviet Forces at Dantzig and were sunk by a torpedo attack by aircrafts of the Soviet Navy using torpedoes:

This is my answer: the Ersatz Scharnhorst class. They were developed as substitutes to Scharnhorst and Gneisenau cruisers sunk at the Falklands Battle. They were projected as armoured cruisers raiders based on Blücher design with superimposed 210 mm turrets. The secondary battery was formed by eight 105 mm guns and twelve 88 mm guns in casemates. Both survived WW 1 and were incorporated in the German Navy. Two more ships were to be built, but the plans were shelved after the Jutland Battle. Eight turrets were stored and were used in the new Blücher class.

Cheers

Pepe

You see, your Ersatz Scharnhorst is way too expensive as a raider and besides building of armored cruisers in Germany, especailly after battle of Falkland is not simply unlikely, its a strategical fault. From Wikipedia:
...The Battle of the Falkland Islands showed graphically how much technology and tactics had changed. SMS Scharnhorst and SMS Gneisenau were sunk by the battlecruisers HMS Invincible and HMS Inflexible. The German armored cruisers were too slow to outrun their pursuers, and their initially accurate gunnery failed to inflict serious damage on the British battlecruisers. The British 12-inch guns turned the tide of battle once they started scoring hits on the Germans, and the German armored cruisers were fatally crippled before they had a chance to close the range and use their superior secondary armament. This victory seemed to validate Lord "Jacky" Fisher's justification in building battlecruisers—to track down and destroy armored cruisers with vessels possessing superior speed and firepower. The German force commander Admiral Maximilian von Spee had been wary of the Allies' battlecruisers, especially the Imperial Japanese Navy and the Royal Australian Navy—in fact he described the latter's flagship, the battlecruiser HMAS Australia, as being superior to his entire force by itself. At the Falklands, he had already deduced the battle was lost when he missed the chance to attack the British battlecruisers in port.
Blucher also is a fault itself, she is a victim of desinformation from Britain about stats of their newest battlecruisers. Also she is one of last armored cruisers ever built, commisionned 1909 along with Italian Pisa.
4x2 superfiring design is a bit too advanced for WW1. First cruiser with such artillery arrangement was Duguau-Trouin, commisionned 1926.
On your place, I would stick to battlecruisers that can do same things as your cruiser but three times better. And leave that guns for coastal batteries.

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«A sea is not a barrier, a sea is a road, and those who try to use the sea as an instrument of isolation soon realize their foe has already put the sea into his own service.». - Alfred Thayer Mahan.

The original Scharnhorst was a slow ship, just 23 knots, equiped with triple expansion engines and with an outdated layout. She had neither the speed nor the armament to fight battlecruisers. Wikipedia is wrong when analyses the Scharnhorst class as the last armoured cruiser. This title belongs to Blücher. The battlecruiser was not a successful concept as we can see in Jutland Battle. Against battleship they show all their flaws. Let's analyze Blücher design. She used a lozenge 12 210 mm cannon layout, which in a eight gun superimposed turbine driven could give a good buoyancy reservation and extra protection, and a 26 knots speed. This is a good start to a new ship able to outrun enemies and to attack commerce shipping. German designers moved in their battleships and battlecruisers projects from lozenge layout to superimposed turrets and they could did this in theirs heavy cruisers designs.
We are in an alternate universe. Everything is right if we use technology available at the time.
The heavy cruiser outlived the battlecruiser. They were very expensive and vulnerable at the battleline. The heavy cruiser was used well after the Second World War and the Ersatz Scharnhorst's could be useful as raiders and scouts.

Here is the Ersatz Scharnhorst after a refit in 1926:

Its hard to do without having any similar analogs in real life and/or SpringSharp report. Still I see no reason to spend money on 4x2 210 mm ship if it is possible to spend a bit more money for much more poweful ship like a battlecruiser or to build two or even more light raiders capable of commerce raiding even better. Then I wonder why we see no ships similar to Duguay-Trouin in that era? Probably because cruiser technology still was not that advanced for superfiring 4x2 desings. Thanks to Washington Naval Treaty that, by the way, created the term "heavy cruiser". Heavy cruiser is not the same thing as armored cruiser. Armored cruiser is the direct precedor of battlecruiser - while heavy cruiser is entirely new artificial class. This can be said about any cruiser. Only by United States and only for coastal bombardment. Britain scrapped all heavy cruisers in 1950s and they saw no action after WW2. True. But light cruisers will be even better raiders and scouts.

_________________
«A sea is not a barrier, a sea is a road, and those who try to use the sea as an instrument of isolation soon realize their foe has already put the sea into his own service.». - Alfred Thayer Mahan.

Battlecruisers were pratically descontinued after WW1. Even Dunkerkes were classified as battleships by France's Marine Nationale. Ersatz Scharnhorst are an extrapolation of Blücher 1929 design heavy cruisers that I posted above.
The principal reason was almost all major navies left WW1 with lots of cruisers with France exception. The majority of French cruisers were obsolete even by WW1 standards. They need to rebuild their cruiser forces with state of art ships.
Ersatz Sharnhorst is pratically a heavy cruiser with a little more armour than usual. It's a technological possibility in WW1 universe. Yes, but battlecruisers were a lot more costly With the exception of United States forces, all other surviving heavy cruisers were obsolete and in disrepair condition. It's only a technological possibility in discussion.

Pretty fair. Thats an afterknowledge tho, the fate of battlecruisers can not be known at the date this ship was designed, but its up to you.
This is the secondary reason. If this technology was really possible in late WW1, we would see Frobishers and Emeralds with turrets and Omahas with superfiring layout. However, no cruisers had superfiring layout until Duguay-Trouin.
For example, one of the very first US cruiser designs with superfiring layout is dated 1923 - Design 292, 11 500 tons of displacement, 4x2 203 mm guns (source - Norman Friedman's book "US Cruisers - Illustrated design history, page 119). I am absolutely sure that for other nations this date is relevant too - Counties appeared in 1928, Leanders - in 1929. German Emden was built in 1925 and had no turrets at all.
I dont say this is impossible, I respoded to statement "heavy cruiser outlived the armored cruiser" that is a bit wrong. Armored cruisers and pre-dreadnoughts were "pair" pretty much as battlecruisers and dreadnoughts. Heavy cruisers (thanks to Washington) were limited and thus served for different roles (BCs in dreadnought era and ACRs in pre-dreadnought era could be used for charging retreating battlefleet, for example - a thing that CA cant do for obvious reasons). Yes, but much more effective and suitable in that time period. Heavy cruiser feels herself incomfortable outside the Washington era because in that time she simply cant be faster than a battlecruiser (because yeah, technology level - no way you can be faster then HMS Princess Royal built 1911, for example, with her 28 kts - this will require a massive and expensive machinery; Later Renowns with 32 kts are an absolute instant death), therefore helpless in a fleet battle (just like Blucher) - cant fight, cant run. Heavy cruiser of WNT era can easily escape from larger enemies - because advancements in turbine technology made during years after WW1 allowed to produce small and powerful engines. But you said that heavy cruisers were used well after WW2? I mean, yes, she can be deployed for foreign station and can be succesful, since she is a relatively fast an powerful ship. But she cant pursuit lighter cruisers because she is too slow (Arethusas of 1913 are capable of ~29 kts) and battlecruisers are too deadly.
I dont want to say, however, that the design itself is bad, no-no. My point is that she is a bit off her era - she uses doctrines of ~1920s and ideas of ~1910s which is somewhat strange to see in WW1. German Empire already was in a harsh conditions and it is very unlikely to see her returning to ideas of an armored cruiser.
But well, this is an alternate universe where everything may happen. Ersatz Scharnhorst is certainly a nice looking ship and that 1929 Blucher is even better (at least to my taste). Best wishes in further drawing

_________________
«A sea is not a barrier, a sea is a road, and those who try to use the sea as an instrument of isolation soon realize their foe has already put the sea into his own service.». - Alfred Thayer Mahan.