im buying intro pentias for a 69 camaro with four wheel discs, front end is stock except for 2 inch drop springs,10 bolt rearend is replaced by a 12 bolt that is 2 inches wider than original. i was thinking 17 by 8s on front and 17 by 9-1/2 in rear. but i dont know what backspacing to use. i want the wheels to be as deep as possible. any suggestions would be helpful, thanks