I hope someone can point me in the right direction?

1972Dart: I switched to a disc setup on my '65 Barracuda last winter, had similar problems to you. I did not bleed the master cylinder first. We tried to bleed it through the lines, but like someone explained, that won't work. We eventually had to disconnect the lines from the master, run short lines up from the connectors into the bowl, and bleed it properly. After that everything seemed to work...BUT I have a leaky seat on one of the connectors. I've taken it apart and redone it a few times, so now I'm convinced the seat or something is defective and I'm going to replace the master cylinder. It was a rebuilt from Cardone. I will use another Cardone one, just bad luck I think. I also bought brand new line fittings that I will use instead of the old ones that may have scored the seat.

On my car, there is no pressure switch in the junction block, that didn't come until 1967 I think. It's just a junction block. I installed a Wilwood/Mopar Performance adjustable proportioning valve in the rear line to adjust pressure to the rear drum brakes. I mounted it under the drivers seat (outside, under the floor) because it was a good place and now I can open my door, reach under and make adjustments. Oh ya, I used small bolt kelsey hayes discs because I have a Formula S sway bar up front and the later style large bolt discs will hit the sway bar.