This was a problem with my BJ8. The fix was way beyond my ability. But as I remember, the first thing to do is to ensure that the frame is proper, both in dimension, square, etc. I had this done with the use of a frame machine and a knowledgeable body specialisit. Next, to ensure that all stays proper, if necessary the frame needs to be reinforced, if necessary by opening it up and welding in reinforcement. If your frame is weak, no matter what you do you will have a recurrent problem.
During the process of securing the frame, the door opening needs to be checked and adjusted if necessary. This is a complex problem which must take into consideration the relationship between the b-pillar, the a-pillar, the rear shroud and fenders. Also, the very dimensions of the door itself come into play, and can be adjusted if necessary.
Properly bushed and shimmed hinges are, of course, a must.
All that being said, the fit of the doors, in my opinion, says volumes about the quality of the overall auto. If done properly, a good fit proclaims that attention to detail carries throughout whatever restoration was accomplished.