1991-1993 parts:
-Wiring harness (tach if you want the tach to work)
-ECU
-Power steering pump AND lines. Unless you like the pump to heat up massively and consider catching fire.
-A/C compressor and lines. (unless you can make a bracket for your original one.
-Distributor and coil
-Intake manifold
-Throttle cable/cruise cable(if you like things all nice and neat)
-Extension Piece that goes from butterfly to intake piping(again, if you like it nice and neat)
-MAF

Procedure:
1. Source parts needed for swap
2. Source a motorset.
3. Remove cooling fan and fan shroud. Remove old motor from chassis. You can unbolt the motor mounts from above or below. Guide the motor out, making sure it doesn't damage anything on it's way out. Pull the tranny with it so that it will be easier to remove, should you be resuing it. Just make sure you go inside and take off the plastic pieces and remove the shifter. And unbolt the driveshaft. Flush radiator with hose if you feel it necessary.
4. Remove A/C lines. You will have to get custom lines made if you want to keep A/C, OR make a custom bracket for your SOHC compressor to adapt to the new motor.
5. Relocate SOHC power steering lines over to driver's side & install DOHC power steering reservoir -OR- install S13 DOHC power steering lines. OR, find a way to mount the original resevoir.
6. Optional. Replace SOHC throttle cable with DOHC throttle cable. Two bolts at the firewall behind the accelerator (and remove it from the accelerator to make life easier).
9. Pull SOHC engine harness. You can either cut it at the firewall, leave it intact and pull it thru the firewall (into the engine bay), or whatever is easiest for you. Don't throw it away - you may want extra wiring, or to keep the connectors for future use.
10. Install DOHC engine harness. Reverse of above. Don't hook up yet!
11. If you're doing a manual swap, NOW is the time to drill out the place for the clutch master cylinder, install it, and run the hardline down.
12. Reinstall everything you took out to prep the engine bay, like AIV, airbox, cruise control, etc.
13. Prepare your new motor. This means whatever maintenance you'd like to perform on it before it goes in, i.e. water pump, vacuum lines, thermostat, reseal oil pan, timing chain job, belts, etc.
14. Reinstall the ka24de into your chassis. Again, watch your clearances. Make sure you attach your heater hoses during this step. They're hell if you don't.
15. After getting the tranny mounted in and bolted down, tighten down the motor mounts. This is important, you don't want your engine can sit corooked and still be tightened down at the motor mounts.
16. Reinstall your clutch fan (or not if you have electric stuff), and install your radiator and fan shroud. Install your Upper and Lower radiator hoses at this time.
17. Start connecting the harness to the motor. Now is the time to do a good job of installing the wiring in the engine bay. Don't attach to the ECU just yet, its coming...
18. Finish installing everything else, like intake piping, sparkplug wires, etc.
19. Your engine bay SHOULD be complete. Don't forget oil and other appropiate fluids. Don't miss the engine ground wires! Now it's time to take care of that harness/ecu wiring.

Wiring:
1. Locate the body harness (under dash harness that attached to the ECU) that attached to your old harness. Cut the old connector off (the one that attached to your SOHC harness) and attach your DOHC body harness connector. Just match the colors!
Yellow/Red --Tach
Yellow/Green--Speedometor
Orange--Ignition start
Black---Ground
Blue/Black---Water temp sensor

There will be some wires left over. These are for the SOHC's diagnostic plug, and are unnecessary. Please note: Your car will NOT be able to hook up to a CONSULT tool.
2. Use a soldering iron to splice the wires together. It makes for a much cleaner job, and a cleaner electrical signal.
3. You need to swap out your tach if you want one that works. No wiring is involved, but it must be done. Simply pull your gauge cluster and remove the three screws behind the tach. Lift and separate. Replace.

DONE!