[SS Tim]

I'd think just putting a set of 71-72 disc brakes would do it for you. A hydro boost if you are going to carry loads or tow a trailer might be a good idea. Adding aftermaket brakes seems like an expensive solution to a non-problem. If you can lock up the wheels, brake torque isn't your problem. Might consider adding in addition to the stock '72 disc/MC/prop valve setup a lever type adjustable rear prop valve when running empty. It would enable you to pretty much turn down the rears at will. Stock brakes are easy to fix on the road and that is a consideration on a DD. New rotors, calipers, hoses, bearings and quality pads will make a reliable "no sorting required" long lasting brake system. Stainless lines and flushing the system every year or two only help the long term.