@coachofmany:
I believe the Iowa class BB width was limited by the Panama Canal, you can see the difference on how narrow it is compared to the Yamato. The Montana class BB added a fourth turret but was equally as narrow, again to accomodate the canal. Even though the Yamato had a 18.1" dia. shell compared to the 16" of the Iowa class, the 16" shell had a farther range. I agree, the Yamato class BB was a pretty ship!
I just read where the locks are only 110 ft wide, so the Montana class would not fit!
One thing to note though is that the Montana was never built, planned but never actually built