A body rear

hey Bad Sport thanks for the imput.I'm set on my wheel combo 5.72 backspace 17 x 8 rim with a 245 45 17 tire.Based on the numbers you provided the 63 B body rear would be roughly 1 5/8 narrower than a 68-70 B body rear.This should pull the tires away from the quarter by 3/4 "on each side.I had 1 1/2 to the leaf spring with the 70 B body rear with the above mentioned tire combo.Also Darter6 I'm going to run the Dr Diff 11.7 rear disc setup.
thanks