Had a chance to communicate with a place today that makes aftermarket master cylinders and I asked about needing a residual pressure valve for drums brakes. Seems nowadays it depends on the design of the MC. If the internal piston is shaped a certain way and retracts quickly enough it will maintain a minimum amount of pressure in the lines for the wheel cylinders to stay sealed without using a separate valve. Their MC's work this way, a separate valve is only needed if the MC is lower than the wheel cylinder. So the answer is "it depends"... I was looking at one of these: http://www.ebay.com/itm/380584877050?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT
Idiot here, so I checked my calipers on the rear and I have the passenger side caliper bleeder at the lowest point, I will flip that bracket and caliper and see if it brings the pressure up