The optimal super-large battleship

I spent much of 1999 drawing very large battleships and battlecruisers. I just opened a record book to a page that has a large battleship drawing with some specifications. The ship carries 9-21in/45, 12-6in/50, 8-4inAA, and 44-40mm AA guns. The displacement is given as 115,000 tons. The speed given is 31 knots. The armor mentioned was 17in belt and 7in + 4in decks. I did a few calculations with the BigGun program and designed the 21in/45 gun. The muzzle velocity is 2,575 ft/sec, and the AP shot is 5,000 lbs. The piece weighs 311 tons. That is using my design coefficients, and may be heavier than someone else's design. The question is: how well does this design stand up with the preliminary design program? I had some sort of problem on my first run, but one goodie is that the triple 21in gun barbette is 45 ft in diameter. I suspect that some table lookup in the power calculations was out of range for a ship of this size! If I give a power of 190,000 SHP, the expected speed is 29.6 knots. The normal displacement is 108,008 tons. I should probably be able to tell what the issue is, with a little debugging, sometime tomorrow.