I think that the best how to article was a Mopar Action piece called stop on a dime. I did the conversion with the 73 up A body discs and went with the later 11 7/8 R body rotors and the
2 pin caliper that takes the #39 pads. I do have 15 inch wheels. You can use the complete
73 Duster set up and be done with it. You do not need the upper control arms and your
lower BJ is the same as the Abody with disc. The only thing to be aware of is that you may have sway bar clearance issues. The back of the caliper piston may hit the end link tab on the lower control arm. If it does either lose the bar and cut off the tabs or swap spindles from side to side and reroute the brake hose to the back of the caliper. I've heard a 15 inch one works. This is a good time to get a 3 piece stainless set from like Russel. They cost about 50 bucks and will give you a better safer brake system. You will need a adisc brake master and an adjustable regulator for the rear. The cost can be high if you use name brand stuff like Raybestos and Wagner. The rotors are available cheaper (chinese) and the loaded calpipers were not expensive but you will eat the core charge. I went 73 B body 2 pin which is considered superior to the floating A-body one found on that 73 Duster. Basically you need the caliper brackets for which ever rotor you use. 79 R body rotor needs 79 R body brackets.
Good luck and it was well worth it. No more boiling brake fluid after the 3rd run at the track.
The price of the pieces cost me about 375.00 bucks. Kits are only a little more but you usually end up with GM calipers/pads.... :wave: