I have a B18B in my '96 DX. Don't let anyone fool you; the car won't win any NHRA titles, but with i/h/e and a type-r tranny I'm running 14's. If your new engine is a different OBD generation than your car, just buy the correct USDM harness. Should only cost you about $100 on ebay. You'll still need the adaptor harness to plug in the under-dash wiring harness, but the cost of the correct engine harness, to me, is low enough to make not having to cut and solder 100 wires worth it.
The rest of this post is only relevant to you if the new engine is the same OBD as your car. Your car is OBD2B, so if the engine is the same, use your car's existing harness. As for the IACV problem, check this link. Works like a champ. http://www.ff-squad.com/tech/wiring/wiring.96-98.jpg
Other than rewiring the IACV, you'll need to extend the wires on the injectors and the O2 sensors. I'm pretty sure that's it. Maybe the MAP sensor too, but I don't really remember. I do remember that I gave myself 6 hours to do the wiring for this project and it only took about 45 minutes. Have fun and congratulations on your swap.:cheers: