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Go to your local parts store and buy some shims that are 1/16 to 1/4" thick. Loosen the lower hinge to body and while a helper lifts the aft end of the door up (or use a floor jack with a wood block under the bottom edge of the door) insert the shims as required between the hinge and body pillar. It will take a little trial and error but you can square up a sagging door with some good results and eliminate that "A" margin you are talking about.I did the driver side door on my 70 because they sagged so much that I had to lift them up to close them. That was attributed to the fact that the pins had worn out so I got the rebuild kit. Changing the pins was only part of the problem, I still have to align them. I did a quick alignment job with washer but I will have to go back with shims in the future. No matter what you do it will take a ton of time because it's almost like art to get them right. I don't know about a sagging body, I think the frame is too stout, but maybe someone else will have some input. Before you worry about the body sagging, try the shims. That could be the problem. Good luck.
Rod