1970 C10 Brake Pressure Problems

[elorenzof]

Good Morning,

Since switching the front from drum to disc on Phyllis our 1970 C10, i have not been too happy with my brake pedal and or stopping. (low pedal, but yes she does stop). the truck originally came with a power booster and distribution block with the drum drum setup. I figured the Napa Master Cylinder / Power Booster combo i purchased were no weno so I opted to get a Classic Performance Master cylinder and Proportioning Valve and ditch the old distribution block used for drum/drum setups. Installed no problem. Going to bleed the brakes starting from the pass rear i have a mytivac brake bleeder thingamajig and it seemed to start out good with lots of air and brake fluid coming out. then it stopped bleeding. Still have suction but no brake fluid. Reservoir did not go down on brake fluid on the rear cavity. So it seems that i sucked all the brake fluid out of the line but i cant get brake fluid to come out of the rear bleeder valve. I dont see any fluid leaking from any of the lines either. I need to mention i did bench bleed the master cylinder before i put it on the truck. Is there something I am missing? Does the new proportioning valve need have something done to it too? I had my wiff do the brake pedal up / down while I opened the valve and closed the valve to bleed that way but nothing was coming out no air no fluid. If someone can please help i'd be greatly thankful.