Just out of curiousity, do you have your tire's section width and height handy?
I don't know how close these cars are in the frame and quarter dimensions so I'll throw these out there.
frame to frame (wheel side) - 38 7/8"
quarter lip (inside) to lip - 67 3/4"
lip to frame - 14.5"
(discussion on measuring for backspace:
http://www.forabodiesonly.com/mopar/showthread.php?t=220183)
