I think the shims were right at a 1/2 inch exactly. Not a typical size that is made but I found mine in Lowes in the hardwood/cabinetry section. One of my screws did not sink all the way and created a hassle when remounting. I had to relift the body and use a different screw. So be careful of that.
Removal of doors: Rear-I ground down the weld on the top of the hinge and used a screw driver and some nails (ground down the heads) to pound the hinge pin out. Sides-drilled out the tops and used a punch and awl to push out the back side. If it wouldnt come out, I drilled all the way through.
I did not weld any hinges. I saw someone else do it and it looked sloppy to me. I mocked up the door, hinge, gasket and strip and held in place with a long screwdriver on each end. then started riveting out from the middle.
Sorry it took so long to get back to you, I have been out of town. Good luck with the build and the doors... they are a lot of work.