Afaik, Over the lifetime game had 4 Yamato-class models:
1) Yamato
2) Shinano (as CV)
3) Musashi
4) New Yamato
And each one was produced mostly separately. Apart from the obvious cases - like no one needs to to model 25 mm AA gun every time.
Correct me if I'm wrong - instead of really possible and sometimes planned refits and alt-history you want us to simply leave anything based on reality back and change stats for ships freely, in a pure fantasy way, just because the visual models may look more historical that way?