wae stopped by and I showed him my brilliant wiring plan, we hashed out a few things, and came up with a short list of stuff we'll need to get it all together. We also tried to re-check some of the wiring that failed my continuity testing earlier, and they still failed. He traced some of the wiring, and we came up with a backup plan for the TCC switch, and were about to give up on the starter solenoid wiring when we had the brilliant plan to hook a battery up. The correct wires at the bulkhead got power when they should, and didn't have it when they shouldn't, sop there must be a little magic going on under the dashboard that the wiring diagrams are not showing. I'm happy we don't have to hack up too much more wiring. Forgot the check the MIL control, but I will hook the battery up again sometime soon, because I think one of my evening projects this week is going to be to fix the speaker wiring, and temporarily hook up the new radio to test it.
The only big thing to figure out is the wiring on the passenger side connector and how to integrate it with the underdash wiring. That'll cover the VSS signal, OBD2 wiring, tach signal (I need to install a tach), my aftermarket gauges, and auxiliary light controls for now. Possibly also a neutral safety switch, but I think the ECU reads that off a sensor at the transmission. There are plenty more connections, and I may run some power wires in for future expansion.
I also realized after wae left that I should not have cut the two red wires at the firewall. They can be re-soldered, and their terminals can be hooked to the alternator.