Gary
First check door hinges if you lift door up and down and there is play need to fix first. Other than that you loosen striker on frame and align with notch in door lock, will have to move striker in or out as needed. Other than that body shop.especially if hinges bad.

oneiloilokano
I seriously doubt it's just a simple matter of realignment on a car that's 45 plus years old. The door hinges themselves are probably worn out. Replacing and re alignment is not easy or cheap. Finding replancements are going to be difficult, but try www.yearone.com or e bay. Maybe if you found a local MOPAR club they can help you scrounge up some hinges cheaply.

doane_nut
The hinges are probably also worn out so that would have to be factored into the cost also.