I have a stock 66 Power Drum/Drum Delco bake system. Don't like the single resv master cylinder. So a trusted site member suggested installing a 67 Power Drum/Drum MC. Makes sense, fit up looks correct. Was considering adding a 1990(ish) S-10 Combi valve which is from a stock Power Disc/Drum set up. (had one on hand at no cost) We are using Inline Tube replacement lines so I asked them if this arrangement made sense. Inline was very helpful in pointing out that the drum drum arrangement was designed for 50/50 braking (front vs rear) and the disc/drum is 70/30. Also, the design pressure for front disc is about three times greater than the rear drums. This would result in the fronts locking up before the rears even moved. Anybody out there have some experience to offer? Is anyone aware of a factory Power Drum/Drum Combi valve from 1980s or 1990s? Combi valves did not become prominent till the later 1970s. Thanx in advance for any help or advice
