I'm considering an A 500 4 speed overdrive for a 72 Duster

If this in response to the cross member fab, then yes. You do have to fab your own mount or buy the one from US car Tool.
Yes it was. All the other one i see they have taking everything away on the body and may bee not thing about suspension.
I have been thinking about this projekt for 3 years but dont want to disform the body but your way is acceptable. And now there is a A500 1989 for sale.