I've got a '67 El Camino, and I am running a 19"/20" combo. 19 X 8.5 front (245/35-19, with 5.25" backspace), 20 X 9.5 rear (285/30-20, with 4.5" backspace). I have Wilwood brakes at all 4 corners, and I have narrowed the rear end 1" per side. No body/fender well mods.