I purchased a CPP power brake conversion (4852BB4) for my 1950 Ford F1 pickup. At the time I was planning to go 4 wheel discs but I eventually decided to keep the 4 wheel drums. I removed the proportioning valve and installed the rest of the setup. Now, I have brakes that are extremely sensitive and will put you through the windshield with very little pedal movement. After checking a number of items, I remembered this was originally a disc/disc setup. It is possible that I have the wrong bore size master? Does the drum/drum master have a larger or smaller bore than the disc/disc unit or are they normally the same. I haven't pulled the master off yet so I don't know what size I have but at this point, I don't know what I need to get if the bore size is causing my issue. Any info would be greatly appreciated!