New brakes with no pedal?

[scotts72heavyhalf]

Im in the process of a 69C10 frame off and just got the truck back togather enough to fire it up and terst out the brakes, I replaced everything did a disc conversion, new master with booster, new lines flushed, bench bleed the new master and really no pedal pressure, the brakes work but the pedal is weak and at fast idle it want to walk with the pedal pushed all the way down, althou8gh no bed on it and the SB is build with the posi its fine off high idle, just a weak pedal, very soft. I had synthetic in it, changed it back out thinking it might be the cause but still the same, vacume shows good and pulls on the booster hose.

Does anyone have any ideas? I have adjusted the drums as well and the parking brake works great, seems hydrolic in nature.

Thanks Guys