Aerospace brakes wont release.

Like the title says, I put some aerospace drag rear brakes on my 91 notch last year. With the stock master cyl and gutted stock proportioning valve the rears didn't really work at all so I figured it was time to upgrade the rest of the system. I finally got around to doing the 3-2 port conversion and (98v6) MC yesterday and am now having an issue with the rears not releasing. I have great pedal feel and they bled out really nice. I tried adjusting the booster rod in thinking it might be out too far but to no avail they are still hanging up. I can spin the wheel by hand (when in the air) but there is definatly resistance. I took it for a short spin and had major brake dust and the rotor was super hot when I got back so I know something is up. The funny thing about this whole deal is that this morning when I took the new master cyl out to re adjust the rod, the rears were still hung up. Maybe I am over analyzing this and this is just the way they will be until the pad's wear a bit but I just would like a second opinion.

thanks a lot.

Thanks for the ideas. I did bench bleed the master cyl before putting it in. Both calipers are free and not froze, I had to push the pisons in to put the new pads in and they all (4piston) went in just fine. You would think there would be pressure at the bleeder screw back there which would be holding the pistons out but when I crack the bleeder the fluid just drips out like it normally would when gravity bleeding. I'm stumped.