Brake issues driving me bonkers!

[supertrkr]

Hey guys. I'm having trouble with nailing down a brake issue. So here's the skinny.
1968 C-10 with manual brakes
CPP Disc brake conversion rotors calipers and spindles.
CPP 1" bore disc/drum aluminum master with prop valve
Ford 9" out back with drum brakes

So here's the issue and what I've tried. My pedal is garbage. The pedal goes 3/4 of the way down before the brakes start to work. I've bench bled the master 3 different times. I used a power blender to bleed 3 16 oz bottles of brake fluid the the system. I clamped off all the brake lines and the pedal is rock hard. I unclamp the rear line and the pedal goes down about 1/4 inch. I reclamp the rear line and undo the front clamps and the pedal goes back to crap. The rear brakes are adjusted up. I know that's telling me that there is a problem with the front somewhere between the clamp and the caliper. Has anybody experienced this? I spoke with a CPP tech and was told I had a problem that had them stumped. Basically they sold me a longer rod and clevis for the pedal against my better judgement. Any advice would be GREATLY appreciated.