Mr. Dorsey used a modern, dual chamber master cylinder from a mid 70's up, heavy duty 3/4 or one ton pick up, without power assist. The set-up stops the truck quite well as a manual system. Once upon a time, John had detailed drawings on the net of the caliper brackets he made. You might email him and see if those are still available. He's a good guy and readily answers questions.
Good luck!
