When the brakes are locked up and the vehicle is hard to move if you crack the the lines loose at the master cylinder a quarter turn then tighten them backup does the brake pressure release on the front brakes?
I cracked the lines loose at the caliper, like I was bleeding them and that works. Should I try it at the master cylinder. It's odd, I bleed the brakes at the caliper, it lets the pressure off, but then will eventually build back up.
You have one of two options either the load sensing proportioning valve in the back is stuck or the lines are hooked up wrong or the check valve in the master cylinder is not releasing the fluid pressure. Because all of these things were fooled with in order to replace the frame only your going to be able to make that determination.