Maybe you can use some of my tricks. Before anything gets cut off doing body work i get the doors repaired.I change the pins if they need it and get them solid .Try to aligne the tops to fit good in the cab frame . Now put the floor jack under some part of the front of the cab were you can jack it up if the cab mounts are bad.Try to get the door line even. After all the heights look correct on the cab mounts to frame, i cut some straps and weld them from the cab to the frame some were were thay wont be in the way to hold the cab steady with out the rubber mounts in. After everything looks nice i remove the door and measure the opening and weld in and x to do the floors and rockers. I tack every thing.Than put the door back on and check for alignment.If its good you can finish up the spot welds. Dont try to weld the floors and rockers in .Spots are how the factory did it for a reason. Seam seal everything when your done. Drill small holes in panels to spot weld(my air flanger does it for me) Just take your time and try to put it back together in the stages that it came apart. You will also have to do work on your panels.I have never seen and aftermarket panel yet that fit correctly. They all need a little bit of work.