Me, I'm thinking of the stuff like the OV Bronco or maybe a revival of the P-51 Mustang; I'm surprised no one ever thought of doing the latter, unless I'm missing something.
There was a proposed revival of the P-51, the Piper Enforcer. https://en.wikipedia.org/wiki/Piper_PA-48_Enforcer
At some point in the 1980's, I think there was a New Zealand company proposing a updated version of another WW-2 fighter. The Hurricane, F6F, some other plane? All I really remember is a mention in a Jane's All the World's Aircraft, and maybe another mention in Air Force magazine? Sorry, I don't remember more to go on.