brake bleeding help.

[zellway]

Well to start off I have a 1967 C20. It's been my truck over 17 years. And it was in my Family from new. I have been cleaning it up and getting some of the bugs worked out of it. The brakes have always been a bit on the weak side. I installed all new shoes and did the wheel cylinders about 3 years ago and this helped. I had the front brake system off a 72 that I have wanted to install for years. I installed all new hoses front and back. Installed recon calipers from Napa. The truck had power brakes so I got the Corvette style master and proportioning valve from CPP. The brake pedal has about 1/16inch play. I bleed the master, installed the proportioning valve and bleed it as well. I went out back and did the R/R bleed with no problems but the L/R will not flow. I also pulled the metal line and air will flow no problem. Also fluid will come from the port on the rubber line with no problem. I also pulled the bleeder and it was clean. I can not get the front to bleed at all. Air will come from the bleeders each time. I also tried the Gravity method and could not get anything to flow. I have a jar that I have used on a ton of other jobs. I hooked up the hose and with the bleeder open each time the pedal is pushed in, bubbles would come out but the level never drops in the master. I went back and rebleed the master cyclinder. And also bleed the proportioning valve. This still has not helped. The brakes are not working at all. The brakes worked before I did all this. Any help would be appreciated, I am kinda at a lost.