viia looks almost like viib........ except the conning tower which differs a little.
Surface ship---->1 deck gun and 2 mini flak same as VIIB
VIIB is faster and has more agility because it has 2 rudders, crush depth might be deeper.
Unless you are someone who wants to challenge the impossible
I doubt you will like it
Now if you want to have a modification on the conning tower, there is alot of mod for that. I think in the visual/mod there is a bunch of modder working on it.