My car isn't as far along as yours but i might can give you a direction to look at. I usually buy Popular Hot Rodding magizine, and alot of the cars and camaro's in them will tell their rim and tire combo's. Just for example the one i'm looking at now is a 69' camaro and the car is running 17x8's up front and 17x11's out back. 245/45R17's front,315/35R17's rear. Doesn't say anything about having to modify the rear wheel wells,but i do know that the larger the rim the more clearance you have for brakes. Thats my two cents hope it helps,but i know how expensive rims and tires can be.