70 Dart Swinger with 275/60/15 E/T drag

Seems like both of you are talking about Dusters/Demons/Dart Sports.
My 68 Barracuda accepts 325/50-15 DRs on 10s, with just the spring offset, and properly centered, even at my lowered ride height......but spirited cornering is somewhat limited. I narrowed the rear for no other reason than to use the 4.5 backspace of the period aluminum slot-mags I so loved. The 295s have tons of room in there.I imagine the other big-tub cars would be similar.
275/60s are about 10.8 section width on 8s, and I thought the Dart tubs are about an inch bigger, depending on where you measure from. Am I wrong?