American Motors: Disc brake conversion, disc brake conversion, piston calipers

Question
The complete brake system of the 82 spirit, spindles, hubs, discs, rotors, dust sheild,etc
I checked the push rod length on the booster, it was 1.187 on a dual chamber booster, I do have an extra single booster ? does that work on this car ? I replaced the original proportianing valve because I thought that was the problem, but the new valve off of the 82 cj did the same thing.
There is a second brass valve block back by the rear wheels ? seems to me it is just a junction block to take the one brake line and make it two ?
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Followup To

Question -
I have a 68 AMX that had the 4 piston calipers from the factory on it, I replaced those with a set up off of a 82 spirit. the brakes when applied tend to lock up front wheels first, seems like especially the drivers side front. I have replaced the master cylinder with a new one, I have also replaced to proportioning valve with one from a 82 cj jeep. I have bled the brakes many times, both manually and with a vacuum pump.
The car still locks up in the front, It is soo touchy that you could never make a panic stop.
What am I doing wrong ?

Answer -
I would try and find a proportioning valve assembly from a Concord or Spirit. Did you replace the proportioning valve that was on your car? It sould have worked OK with the Spirit brakes.
Make sure the pushrod going into the master cylinder isn't partially applying the brakes.
The master cylinder on the AMX w/disc should also work with the Spirit brakes.
Did you replace all of the front brake components,i.e. spindles, too?
Kevin

Answer
Did your AMX have a single diaphragm booster? In the original single diaphragm set up, the rod length is probably around 1". Measure the depth of the master cylinder piston where the rod makes contact, then measure how far the rod sticks out of the booster. There should be a little clearance (.015") between the rod and piston. Adjust the rod accordingly. Or, try making the rod shorter and try it. Your master cylinder could be applying pressure to the brakes before you even hit the pedal.
You are correct about the block in the back, it is just splits the rear lines to each wheel. Please drop me an email at kepilotte@yahoo.com and let me know if this helps. If not, I can make some calls.
Kevin