Shipbucket

They are on a CV so it lets you park aircraft (or at least move/take off/land) over the top of them and therefore makes flight deck bigger. (The guns on BBs did not have the same shape the flat ones are MKII mounting with MKIII guns if you read the pic, may I suggest WWW.navweps.com for more info)
Also to raise the bow (for sea keeping) and yes you can have 2 decks (with or without the front running right to the bow or just as a superstructure) (the 2 deck set up for Kongo is really a 1905-1915 thing, IMO larger later ships tended towards flush deck due to size and strength and yours is BIG )

Looking at the Navweps site has really helped me out for figuring out armaments. My thoughts are this: Have the ship designed in a period of roughly 1920's level technology and priority for weapons. Then overhaul the ships 2-3 times to add new weapons and replace old ones (especially AA).

Here are my thoughts on weapons loadouts:

Initial armament:
15 -19.7" guns in triple turrets. The guns are still technically 22" guns, but their liner has been 'upgraded', reducing the gun down to just below 19.7" or 500mm exactly.

24 to 45 -6" Mark 1 guns in triple turrets. Ive revised the 10" guns down to a much faster firing secondary armament.

80 to "alot" -6" Mark 3 semi-DP guns in twin pseudo-casement 'between decks' turrets. I say Semi-DP guns as while they can hit air targets, they aren't particularly good at it and don't have the fire rate for it anyway.

Numerous 85mm single AA guns. An early, heavy anti air gun that is breach loaded.

Numerous 25mm AA guns in single mounts. An unreliable, somewhat awkward gun that was slated to serve as a stepping stone until a better gun could be produced. Lacks good fire rate.

Numerous single .50cal and .30cal mounts, mostly .30 cal water cooled guns. Reliable and worked alright against early 1920's/later 1910's era planes.

First re-armament:
85mm guns replaced with a new, advanced 60mm rapid fire AA gun in quadruple mounts. Trades a larger shell for vastly faster fire rate, greater accuracy and higher velocity shells.

25mm guns replaced with new twin 30mm guns. Very similar to the German MK101 but with a lengthened barrel.

All .30cal mounts replaced with twin .50cal mounts.

Second re-armament:

36-48 Mark 8 6" guns in DP twin mounts to replace triple Mark 1 turrets.

All Mark 3 6" guns replaced with Mark 8 guns, granting them true DP abilities.

Not sure that big rebuilds are worth it without treaty's but anyway,

I think you should divide all numbers in 1/2 you can then reduce the size by a 1/3 and the cost by at least a 1/4 (or more depending on how corrupt your shipyards are).

Early,
looks on (the 6' DP will not work but you are allowed mistakes makes it more realistic)

1st rebuild,
60mm rapid fire AA gun in quadruple mounts is very 1945+ but the 30mm works just keep the 85mm (and fit a few more by removing a few 6')

2nd rebuild,
The problem is that the new (MK8) will be so much heaver and bigger than the old styles (MK1/3) you will have to rip out the decks to do it (remember turrets have long deep 'stalks' below them, and newer ones have bigger stalks) IMO not worth it unless you are replacing the engineering and deck protection etc (not worth it without treaty and you are taking a surface BB in 1950+ so obsolete)

MK 1 = 6"/50 (15.2 cm) BL Mark XXIII triple Mark XXII: 146 tons (148 mt)
MK 3 = 6"/50 (15.2 cm) BL Mark XXII twin 168,000 lbs. (76,204 kg)
MK 8 = 6"/50 (15.2 cm) QF Mark N5 twin Mark XXVI: 156 tons (158.5 mt)

IMO you could just improve the ships in the 30s and add 85mm and 30mm then do a single big rebuild (just post WW2) with the MK1 becoming MK8 and the 85mm and MK3 becoming say twin 3'/70s, not that it would be good value for money...

I think what I am going to do is shift fire rates down to be more in line with a early 1940's level of tech. All of these guns are native to my world, but I had to base them on real world guns to get an idea of realism. So the 60mm guns will likely lose some of their fire rate. I also initially debated having the early 6" guns in semi-casements be 8" guns instead. I am not revisiting that idea.