Depends a lot on how close of a match you can find. You might need to roll the dash out of the old truck as well and swap that over. Just like how they are built, the dash goes in and out as a whole. That should clear up any wiring mismatch. The hard part is how do you plan to get 2 vans seperated at once? You pretty much need a shop with 2 hoists and a lot of open floor space. It is amazing how much floor space a partially disassembled vehicle takes up, and you are doing it double. Presuming the plan is to drop the rusty shell onto the donor chassis and sell for scrap. Scrap is the better idea then trying to make it running and sell as a driver. At that point you have mixed VINs on body and chassis. As long as you have the paperwork for both vehicles, you are good. Sell the crusty turd and it gets reported stolen or something evil, that VIN is partially attached to what you own. Several years from now, when going through a DMV inspection moving into a different state, or whatever currently unforeseeable event causes your van to get a thorough inspection and they find a VIN off a stolen vehicle there gets to be a whole lot of splaining to do.
Swapping just the 4WD parts over is probably the better way to do it.