It really doesn't have that much more than the original design, though. The only difference being using the twin turrets in place of the multiple single mounts on the original, and replacing the two aft main gun turrets with the Sea Slug.
That is quite a bit more. Both the 6" and 3" were true monsters, both in terms of weight and in terms of volume.
The 6" weighed half again as much as the Swedish guns and due to it's high rate of fire required a bigger magazine. The 3" weighs twice as much of the 57mm, and where the 57mm were a so called low impact design (In terms of hull) the 3"/70 was infamous for just how much space it took up. And then there's the Sea Dart. Like all 1st gen naval SAMs it was heavy and required oceans of space.
Your drawing actually shows that quite nicely. In order to accommodate it you've had to ad a superstructure that's half a deck higher than what was there before and three times wider. And to top it all off you've added a
much heavier radar. So no, it's not even close to what the original carried.
The 40mm is there because I had a big open space and no idea what to put there. I know the firing arc is crap. I'm open to suggestions on what else to put there.
That's never a good reason to install something. If, after you've added all the bits a ship needs, you end up with a bit of open space you're just lucky. Having an open space is not a bad thing, in fact it tends to be a good thing. It gives you somewhere to put new kit when you decide to upgrade it.