Just helped facilitate this swap for a friend of mine.
We picked up a beat up 72 1/2 Ton and took it to a friend of mine's shop where he pulled the front spindles, A-Arms, PS pump, Box, Master Cylinder, and the rear end and swapped them to the 65.
Ended up putting a new Master cylinder in as the one off the donor was leaking. Also went with 2.5 drop spindles and drop blocks in the back although it could have been done with the stock spindles just fine. We ended up selling the rest of the donor for about a $150 profit overall with labor I think the whole thing ended up costing about $2500. The truck drives great stops wonderful and now has 5 on 5 wheels. The 72 parts are bolt in with the exception of the power steering pump which will require some bracket work if the truck has the 283.
The guy that bought the donor turns out he had all the parts we needed off a truck he parted out a few years ago and plans on putting the truck back together and putting it back on the road.

The only minor thing is the higher ratio rear from the 72 yielded much better highway speeds but the 283 and the Powerglide is a little anemic at low speeds but in this case this trucks hard working days are over it's going to be a fair weather cruiser.
Mongo

Mongo's Garage
Vintage GM Truck's & Parts
https://mongosgarage.com