72 Duster Resurrection
If going discs both a shiny new kit, and a 73 up A body will put you into a larger bolt pattern. So does M body brakes for about the same or cheaper as A body brakes, but much easier to find these days. As a matter of fact M body usrs the same disc rotor as A body, and its spindles have a bit better geometry.
If i can recommend M body disc brakes. Get everything from the spindle out from a 1984 to 1989 fifth ave diplomat or fury. These come with larger 2.75" piston calipers. A body ones dont. You will have to also get A body 73 to 76 disc brake big ball joint upper control arms that use the K772 ball joint, A body disc brake flex hoses. 73 to 76 A body disc brake lower ball joints.
The mount bolts that attach the spindles to the lower ball joints you can get 4 grade 8 bolts and locking nuts (not nylon lock nuts) to attach M body spindles. I also recommend using the M body proportioning valve, and an M body master cylinder. You can buy an adaptor on ebay that converts your 4 bolt firewall attach point to 2 bolt for the late model master cylinder. The M body master cylinder is still SAE fittings, and there is a groove in its piston bore in the back to accept your original manual brake pushrod.
Fifth ave rims big bolt pattern wheels are a 15x7 steel wheel and can look really cool painted up with dog dish caps on them. My local boneyard sells em to me for $15 a piece without tires.
See below pix for master cylinder adaptor, and bolts needed to attach M body spindles