In the past I had fun reinventing battleships by swapping parts around.
Here is a BBG version of Nagato, based on the US battleship Mississippi testing SAMs.
Here is a version of the KGV if she’d been built earlier with 15" guns
A Soviet 1950s battlecruiser based on a drawing I found on a Russian site.
I’ve more, which I’ll post later if people are interested. And I’m certain I’m not the only one who has such strange ideas!