There is a thread on supermotojunkie.com, but you have to sign up because it's in the members only section, where a guy does a body swap. It didn't look that hard other than lots of wiring to swap over. But I guess that stuff just unplugs, and plugs back in.
On another note, I live in New Orleans %85 of the time. I can get you a van body fairly easy here. Very high mileage E series vans run around 3k here. And of course, not a spec of rust.
I travel all over, so for gas $$$ I could possibly bring you/meet with said van.
A good place to talk to about that would be:
Victory Motors
1917 Airline Dr Kenner, LA 70062
(504) 467-3650
They have a van boneyard too. So you might could buy a non-running one.
Link on SMJ:
http://www.supermotojunkie.com/showthread.php?50214-Van-SM-Haulers-ONLY
Hope this helps.