8 3/4 find

I got what I think is a good find on a 8 3/4 489 sure grip with 3:55 gears but its out of a
B body. This will be going into a 70 Duster . I'm just throwing this out there. The Duster fender wells look wider then my 68 Dart and I know there both Abodies 57 1/2" in length . Would it be possible to mount B body rear 59 1/2 " with out shortening it, just move perches . Not planning on overly large tires . I don't have the rear yet so haven't matched anything up
just running things through my head.