Easiest way to do it would be get a harness that puts the pcm under the hood. Most Riv's retained the pcm in the passenger compartment while most other cars went to the engine compartment for the series 2's.
Swap engine, trans, and wiring harness. Then make an adapter harness to interface between your engine bay and firewall connectors. Connect only the wires needed like speedo, cruise, gauges etc.
Basically you'd map out the two harnesses and determine what needs to be connected. Probably about 10-15 wires.
I know that I kinda make it sound easy, but when you really get into it, it's not tough. I've also done this type of thing as well as converted a 96 Riv to a 4T65 by adding 5 wires into the harnesses, changing the trans connector and swapping the pcm to a 97 for ease of programming.
