Doors are a first class pain to rehang. if your hinge bushings are good and everything is well aligned and your fenders are off drill locater pin holes through all 4 mounting points. 2 on the body and 2 on the doors then you can  get everything bang on.   otherwise start with a 3/16ths or 1/4 inch thick strip of wood on the lower door jamb to set the bottom gap even and then work the back gap even.  have a spare set of hands available.   make sure your doors are dressed as the weight of windows and stuff effects how everything lines up.

OhSix'

I drew around the hinges with a magic marker so I could line them back up when I put them back on. An extra pair of hands is a must to keep the frustration level down (not to mention chipped paint). The 72 doors are much lighter than the later doors with the crash bars but you still need help.
 
71HANTO

I concur with both notes regarding weight of doors (surprisingly heavy) as well as the need for a second set of hands. When mine were reinstalled, we used a towel at the lower edge, set the bolts to medium tightness, and used a jack for upward/downward motion for alignment. Mine were particularly tricky because I removed the hinges completely from the door and the body to get them cleanly repainted, and rust removed from beneath. With all the guidance here you should be in fine shape.

Chris