It is mostly parts swapping, the basic stuff---belts, hoses, air intake piping, and throttle/cruise cables. The only "modification" you need to do is the right exhaust pipe has to be shortened behind the catalytic converter. Other than that it is bolt in, plug in. Same transmission, computer, and everything else can be reused, as long as you have a good complete donor engine with all the accessories on it---ie starter, alt, ps, & a/c pumps.
If youre interested, I have this book that will tell you everything you need to know in great detail: