Centerline Convos (2) 15"x 4" & (2) 15"x 7 1/2 SBP

What is the backspacing on the rear wheels? A friend of mine would be interested if they would tuck inside the wheelhouse. Would probably have to use the 3/4 inch offset spring hangers. His car is a 69 Formula-S 383 coupe.

I just looked at the Centerline site. The 7.5" wheel is only available with a 5" backspacing. You'd probably want the offset spring hangers.