The steel rims are 15" and according to my Marti report my car was optioned with competition suspension and F60x15 wide oval raised letter tires, so I believe they are correct for the car. ...
But I really think I'll stick with the Cleveland. Yeah it burns some oil on hard acceleration, so a rebuild is in the future, but I like the idea of the original motor and trans in the car.
I like the original setup with the wheels but I'd rather finish the look with the trim rings. You might try and go with 15x8 steel wheels in the back and your 15x7's on the front but still run the trim rings and caps. To me, that is the ultimate cool setup. It gets a little more tire in the back. Looks tough but not too far out there.
I like the original engine setup (or if not numbers matching, I really like close to correct). Prefer Clevelands but I've seen some nice 302 cars now sporting 429 or 460's and looking very good.
For me, I don't like the newer motors sound as compared to the older motors. I'm sure some of that is the muffler setups...
Best of luck in your build and enjoyment of your convertible!!!!!
Ray