Bill, you really need to decide what you want to run for tire size before you go too far. IMO the tire size, and more important the tire profile are a key factor in the car looking "right". For me I simply cannot abide a set of rubber band tires riding on Donk wheels for any street rod or muscle car. I want to see some sidewall, thank you very much! Like Dave says, your tire diameter is a critical value, and a fat fender car is different from a highboy in what's "right". On a highboy the old tradition is a six to eight inch rubber rake, i.e. 31" rear OD, 24" front OD hits the middle. Pick your tire OD, then focus on the profile to get your wheel size, and set up your suspension to achieve the ride height that you want. It doesn't matter what the original tire/wheel size, ride height or Corvair dimensions were.