69 Mustang Sports Roof issues????

[1960LesPaul]

I may be picking up a nice conditioned Mach 1 clone with a fresh 390 Big Block. What issue do those cars have when pro touring. Such as, I know I can fit a 10 inch wheel under my 72 Chevelle but what kind of size will tuck in under a 69 Stang without cutting. I know on a 65 a 17x8 is about it.