So i just started messing around with some old guitars i had (taking them apart etc). A friend of mine has a BC Rich Mockingbird from the bronze series and it has a couple missing parts and the wiring is messed up. Besides the neck being pretty worn, there are two machine heads missing. I'm going to try to restore it the best i can using parts from a Squire strat he gave me. I happen to have a warlock from the bronze series as well, but the wiring is messed up and i didn't use it much. So i thought i would take the machine heads from there, but they didn't fit good. I was thinking of just exchanging necks, both are pretty much identical, 24 fret, basically the same scale length (i think). Would it be wise to do this? and is there any danger in just taking a neck off of a guitar and re-attaching it, like will i have changed something just by doing that?

as long as they're the same scale length and dimensions there's nothing that can really go wrong unless you're a pleb and make something go wrong.
Belief is a beautiful armour but makes for the heaviest sword.