Morning Magnon, about your removal of the hinge plate, making locator holes seems like the best idea, if you don't end up replacing metal in the process. In addition to making the locator holes, I would take measurements from know position on the inner door structure.(ie top measurement from top hinge plate and inner structure to a known point on the hinge plate you are removing, doing this assures you if there is an "OOOPS" somewhere you are swearing at yourself.I have a question about removing the lower hinge plate mounted to the door shell. I need to do some repair to that corner and there is a lot of rust to deal with. Has anyone removed the hinge plate from the door to clean up rust and weld it back in? It wouldn't surprise me if there's a lot of rust between the plate and the shell. I can find most of the spot welds. My plan would be to drill 1/16" alignment holes to get it back to the proper place. Drill out the spot welds. Media blast. Do the repairs. Paint and reweld.
This is what I did on my 67 that I am resurrecting, this thing is FULL of rust and I have replaced copies panels and structure.