I've got Cray Scorpions from a C6 fitted to my 2002 Camaro. The only requirements were 5mm spacers all round, and a little judicious metal removal on the edges of the rear axle bump stops, but nothing that interferes with their function. A C5 should be a lot easier.
Tyre sizes are 245/40R18 front, and 285/30R19 rears. My Avatar pic is one of the rear wheels. Dish is similar both ends. Just be wary of buying proper chrome-plated wheels. Once they start corroding, they're almost impossible to repair. Almost my only choices are a) after scuff removal some gentle blasting to key the surface, then paint over the chrome in chrome-like silver metallic etc, or b) buy new wheels!
There's a good website that lists all PCDs, bores, offsets etc for almost all cars, I used it quite a bit.
Chevrolet Corvette 2002 - Wheel & Tire Sizes, PCD, Offset and Rims specs