Brake combination valve question

[earl84]

I have been just barely getting my truck on the road and driving a little. Working through MANY little things slowly but surely.
Anyway, took it out today, and the front end had kind of a shimmy. Did not feel through the steering wheel at all. Took it to the local tire store and jacked it up to check the balance on the wheels, even though I really didn't think this was the cause, but I felt like eliminating the easy things first. When we jacked it up, the front tires were not turning freely at all. The brake calipers were grabbing the rotors. Front end swapped for a 79 C20, used the 66 brake booster, 79 master cylinder, hard lines from a 1/2 ton and all new rubber lines and all new brake components. The guy at the store seemed to think the combination valve might be bad. I got it home and took the master cylinder loose from the booster to try and eliminate a bad adjustment on the push rod as the culprit. When totally loose, the tires could turn easier, but pads were still grabbing the rotor.
Do you think this combination valve is bad? I am having a hard time locating a new one. I do not have the wire hooked up for the light. I also read something about having to center the valve??? Any help would be appreciated.
Oh, I took the temp of the rotors and they were up about 300 degrees. They were brand new. Do you think they are still good? Should I have them turned? I have not checked runout on them yet, too damn hot, haha.