1971 Firebird Suspension

[7firebird1]

Hello all! I have a 1971 Firebird that I am doing and I have a small issue. I am setting it up to be more of a Pro-touring type car. I bought 20X10's for the back and 18X8.5's up front. The wheels look good on the car but I am having clearance issues with the rear inner fender lip and the tires. The way it sits right now is fine but after I install my Hotchkis TVS System, the rear tires will probably rub the inner lip of the quarter panel. The car has a 12 bolt posi in it and right now I don't have the extra cash to be buying a narrowed rear end. The rear end has drum brakes on it; I thought maybe when I convert to disc in the rear it will give me maybe an extra inch or so to solve the problem....??? Up front I would also like to draw the front wheels in a bit also, maybe with some aftermarket A-arms. The front already has disc brakes, but I wondered if I could swap out for another spindle or something it might save me some space. I would greatly appreciate any feedback and input. Thank's guys, Tim.