The AE82 will be running a 4A-C, the 4A-FC was in the later AE92s etc.
The head will go on to the 4A-C and has been done before but it will require almost the same amount of work as dropping an entire 4A-GE.
By far your best and easiest option would be to find a AE82 twin cam donor car and moving the entire package with the loom, rear brake setup (they came with disc brakes, not drums) and also the fuel tank (for the better pump etc). This simplifies everything as you don't have to modify much at all and you can just use all the Twinky wiring.
If you're serious about it, donor car is the way to go unless you find a complete package of everything you need. Which is what I will be doing when the 4A-C in my AE82 shits itself.
There's heaps on information out there on this as well. These forums, ae82.net and toymods are your friend.
P.S http://www.rollaclub.com/board/forum/13-general-mechanical/ that's the place you wanna post mechanical questions!