If your car is a street car without a roll cage, I would stay away from fiberglass because you'll have zero protection in a side impact. Fiberglass is OK for a racecar. The picture below is one of my doors I got from UP22 (link below then scroll down to bottom of page). I put in MANY hours smoothing the waves and building up/shaving the door gaps to factory specs. That being said, 71, 72 metal doors are much lighter than 73 up when Ford started adding impact bars. You can use 76 up doors if you retain the 76 up top hinge assembly. Side note, your 73 door panels are not a direct fit for 71-72 doors as the pull handles are totally different. Some advice from experience...n ever buy anything from the guy selling fiberglass parts up in Canada.

71HANTO

http://www.hairyglass.com/pinto.html

http://www.up22.com/amx68.htm

Thanks guys for the info.  It makes sense what you said about the lack of safety with fiberglass doors.  We'd really rather have metal ones, despite the weight issue. 
We were advised by a member that someone in Taylorsville, KY, may have some doors or know of someone.  We don't have facebook (don't want it either) to look him up.  I don't want to put his name out there.  (Don't know if that is good pc etiquette or not.)  But if someone knows of doors we need them.