One thing that was done sometimes was to move the body slightly toward the rear of the chassis. I know a Superstocker that did this. I don't see how that alone would affect the doors, though. You could check the body mounting points for signs of modification.

You might also see if the door openings are tweaked a little, and no longer square. This sometimes happens in a accident, or under heavy strain. If this were the case, you have to stretch the opening diagonally, using a hydraulic jack and some wood or pipe to reach the two corners that are too close. I've had to do that myself.

Just study the door "fit", and common sense should tell you what needs to be done.