Slick 60's

Im wanting to do a 2wd to 4wd conversion. Ive got a 66 short bed and the donor truck is a 78 Bronco. My question is should I just buy a lift and use the drive train? How can I make the swap easier?

I just finished up doing a 65 long bed onto a 78 3/4 ton frame and it was super easy. Other than a few questions I had that were answered by the guys here. You may want to measure your wheelbase. I want to say the bronco has a shorter wheel base than the short box.

It is thats why Im asking. From what Ive heard that I can buy a lift kit and bolt the axles in place. The only problem with that is the 2wd crossmember is supposed to hang alot lower so you have to get like a 8"+ lift. Not that Im apposed to that but I dont wanna order lots of useless parts.

Probably end up being easier moving the 4x4 items to your frame, unless you are up for plenty of cutting, fitting and welding. The Bronco frame and wheelbase IS shorter. Either way, you will still end up making some steering column and other associated modifications. If you are referring to the engine crossmember, easiest answer is to change it out with the other Bronco items.
I'm not sure I understand your reference to needing a lift kit. I can tell you I've had both F100's and Broncos with extreme lift kits, and to make them even tolerable, IMO, you are going to spend a BUNCH of money! Anything less, and you're just going to WASTE a bunch of money! Custom shafts, adequate dampening, and, of course, the widely discussed pinion angles all come into play.
I've got a complete setup on my shop floor; I just have too many easier projects to complete before I even consider doing a moderate 4x4 conversion correctly. Easiest solution, as posted, is to find a short bed bump or dent donor. The hardest part of that is apt to be finding the donor.
Paul

easiest conversion is your truck body on a matching wheelbase frame.
anything else involves lots of time and $.

early short 4x4s are kind of hard to find, mid to late 70s gets better.