For example that ship you want to use: it was presumably an dream design by Hitler drawn on some paper. I think it is just one of many myth.
It's a known internet-era hypothetical that got picked up for a book about Napkinwaffe designs. While it's easy enough to imagine Hitler demanding Dora guns in turrets, it didn't happen.
And I would say Yamato class is "probably" the limit of how big a battleship should be, before it is starting to be to big for surface operation. bigger than that: an island with gun's on would be more effective as an battleship!
I'd push the limit a bit higher (to say 80-85k tons displacement) if just to get a Montana battery (twelve 16" Mk 7s with super-heavy shells) and armor scheme (designed to counter her battery) up to 33 knots. You're still spending a lot for those extra 6 knots. Anything bigger in the pre-OGW era and you're not getting your resources' worth out if it.