I am having an issue with a disc brake conversion. I bought a complete 1973 Duster front disc brake setup from a guy that had it on his 68 Dart. I put everything on my project Dart along with a new master cylinder. After bleeding the system I can't get a tight pedal. After some investigating I found that if I hit the pedal once it will go to the floor but will get some gripping at the front brakes. Looking at the rear it takes two or three pumps for the rear wheel cylinders to expand. Does this sound like the wrong proportioning valve? I know they make one for the drum front and drum back, and another for disc front and drum back setup. It will be a pain to replace now with the motor in and limited space. Before I go out and buy a new valve I could use a little input from a brake expert or knowledgeable person. Thanks.