It is simply having the right parts, and switching some wires. Use the S14 motor with S13 dohc harness, mafs, coolant temp sensor, ecu, and distributer, and you should be good. The parts that you *might* (don't know off the top of my head) have to rewire are the "F9" and "F10" or "battery area" wires, and the dash plug. Don't forget the S13 dohc tach for your cluster! AC and PS are a whole nother story.

If you have no clue what I just said, call a professional. Help from the forums can only go so far before both of us lose our minds.