Brake Advice Needed

[GreenSnakeDoc]

I've made some modifications to the brake system and ended up with a bubble someplace that I can't get out after running 3 quarts of DOT 3 through all four calipers. Initially, the brake pedal will go to the floor with ease. Three or four quick pumps brings it up a lot higher to I stop the car reasonably. However, the pedal is still mushy. This tells me I've got a bubble.

1. In Front, I replaced Mustang II 9" rotors and caliper with 11' rotors and
80's GM single piston, slide pin calipers. I've found where the bleed hole is inside the piston and have rotated the top of the caliper back about 10 degrees to put the bleed hole at 12 o'clock.

2. Removed the factory brakeline junction box, replacing it with a Tee for the two front lines and putting an adjustible proportioning valve in the line to the rear calipers. Totally split system.

3. Installed a new Master Cylinder and "bench" bled it with the plastic adapters and tubes supplied. No bubbles from either piston.

4. I've checked the bleed hole on the rear axle, and it's on top. It's supposed to be from a Lincoln Versaille, which had a narrow axle perfect for the track width of a Cobra replica. I'm assuming the rear calipers with parking brake feature are the ones originally on the axle, and so the bleed hole should be on
top.

I've got speed bleeders on all four calipers so I can pump the peddle myself; however, I can't tell if any bubbles are coming out with the fluid. Maybe I should try my vacuum bleeder with some teflon tape around the bleeder valve?

I had two problem areas in making these changes. The hard line to the left front flex hose would not loosen with a line wrench, so I ended up using a vice grip and re-tightening with vice grip because flats destroyed. The hard line comming out of the front of the MC that goes to the rear brakes also wouldn't loosen with a line wrench, so it was vice gripped to disconnect and reconnect. Is it possible to have air leakage at these connections without dripping any Dot 3? I'm thinking of replacing both these lines. Also, is orientaion of the proportioning valve important. The knob is on top at a 45 deg angle for easy access.

Any and all suggestions and recommendations will be greatly appreciated.