Mad Dart, On my 66 I have about a 1/2 inch clearence between the sidewall and the leafspring and 1 inch of clearence to the lip on the quarter. The problem with going to a 8 inch rim with the same 4.5 back space is not only do you move the rim out 1 inch you move the center of the tire out to. With a 7 inch rim the tire is centered in the wheelwell on an 8 it offsets it to the out side. A good freind of mine has a 69 340 Swinger, he has 275-60-15 m&h drag radials on 7 inch rims, they will scuff up in side the wheelwell on big bumps and dips with some one in the back seat, he had 235-60-15 bfg on 8 inch before (with same back spacing) rubed the side walls off on the lip of the quarter on all turns,bumps ,and dips. P.S. Mickey Thompsons section width on a 255-60 is measured on a 7 inch rim.
