[Mkelcy]

I have a '67 RS/SS and faced the same dilemma. My decision was not to cut up the body, and only to do mods which could be easily reversed.

So, stock subframe, AFX spindles, Bilstein shocks, IROC box, SPC UCA/LCA, AFCO springs and adjusters and Hotchkis sway bar up front; Flex-a-Form composite leafs with swivel bushings front and rear, Bilstein shocks, Fays watts link and sway bar (if needed) out back; Hotchkis SFCs (I like DSE SFCs but, again, didn't want to cut the body) and solid subframe bushings.

I'll run 275-18's in the back and 245-17's up front - because that's what you run on cheap and readily available C5 wheels. Frankly, unless you're a great driver, you'll never know the difference between these tire sizes and what you want to run - particularly if you're contemplating a 40mm+ difference between the front and rear tires.

I have a '68 which has been minitubbed, and for a variety of reasons - not the least of which was trying to avoid any tire rub under any conditions - I'm running 295's out back. However, they'll match up well with the 275's up front and what I'm going for is good balance and handling, not the most impressive look in the parking lot. That said, YMMV.