Thanks for all the responces. I have been trying to source out a used door. I would have gone to the parts heaven swap meet but I was chasing motorcycles all weekend. I had thought about using the crimper but I picked these up instead:
Butt Weld Clamps Kit
I will be tig welding the joint if I go that route. So proper gap, tungsten and filler rod is all important.
And I agree that the 3M stuff is good albeit expensive. Maybe I will give a shot to repairing the lower section and keep an eye out for a good complete door.