Rear wheel/tire math problem, 69 Dart...

Both wheels have exactly 2.25" offset, so your tire centerline does not change. The 295 is 1.05" wider per side, so you have 1.05" less clearance.
I don't think so
Your adding 3 Inches to the overall width of the drag radial wheel, but your adding 2 inches of backspacing, which is half and inch more then half the 3 inch increase, which means it moves the centerline one quarter of an inch...i think