NEED 1973-76 Disc Brake Distribution /Proportioning Valve

Still working on my brake problem (see various topics from billkrz). I have been informed that I need the distribution block (where all the brake lines meet) for a 1973-1976 A body. This is because my 1968 Dart which originally had drums has been switched to 70-72 B/E discs which have a 2.75 " single pot caliper. The story goes that the original drums use the same/similiar quantity of fluid as the 4-pots. However, my B/E single pots used much more and this is why my fronts aren't working. (At this point I'm willing to try anything!)
Does anyone have one or know a source?
Tried Inline but they only sell 1 type for 1967-1974 Mopars (so..they must be wrong if the comments above are correct)
Thanks,
Bill