rebuilt calipers are dirt cheap & reliable. You might go to your parts house & eyeball one of em & compare the piston recess depth to yours. If you do get new ones get ones for a 76 A body (2.75" bore) cuz the more front bias the better (same price too). If you do sand have a method to get em straight, (I'd be leery) & if hand sanding going in a figure eight motion works the best for an even/level cut
I would recommend not using the 76 up calipers. I did this, and due to the larger bore, I had to change from a 15/16 MC to a 1 1/32 bore MC. The 15/16 did not move enough volume to operate the larger calipers.