Don’t think it’s going to work in your dart 4.5 bs is better for big bolt pattern axles. Better fit would be 15x7 4.25bs with a 255 60 tire
on a 67-69 barracuda you can fit a 275 60 15x8 with 4.25 back space small bolt pattern axles with no modifications. On a dart you will need to relocate springs etc.
