That Ford and Chevy are pretty much the same. Both are carbureted, 3 speed auto, small block engine. The only real difference is the Ford has a full frame. The Chevy is a uni chassis. The Ford will feel alot heavier on the road, and the Chevy will feel lighter. The Ford is prime for a 4x4 conversion, while the Chevy not so much... The front suspension on the Ford (TTB) is alot stronger then the A-arm Chevy, and can take a real beating while off road. Any NAPA auto parts store in any town in any state will have parts for either in stock. The Ford C6 is abit clunkier then the GM T350/400. The ford is nearly certainly a 2v carb, and chevy most likely a 4V.
The Chevy will have virtually zero emissions equipment. The '82 Ford will have a smog pump, EGR, Catalyst, etc etc etc...
Both vans can be easily repaired with only hand tools.