One of the things that left with the engine and the ECU was the connector that goes to the reversing switch on the transmission. The switch is still in the transmission, but there's no way to connect it up to the car. I had to find the line back in the trunk that ran to the reversing lights. It turned out to be easier than I'd hoped. Once I isolated which wire it was, I cut it as far back as I could in the wire loom that runs into the trunk and spliced it to a new wire that runs to the switch. On the other side of the switch, I have a wire running to a power source. Problem solved.
I also ran a 12 volt line back to the battery box in the trunk. and one from the fan that will vent the battery box in the trunk. Those two lines will be connected together with a temperature switch in between them. When the temperature hits 122, the fan will kick on and force fresh air into the box.
I added a new relay in the electrics bay. This relay will work as a check for the heater. I'll hook it up to the car's ventilation fan, so that when the fan is turned on, it will power the new relay. That in turn, will power the switch for the heater in the cabin. If I turn on that switch, it will power the big contactor/relay I pointed out a couple days ago, and that will turn on the heater. Why so complex, you ask? This will ensure that the heater can not be turned on unless the fan is already on. I really want to avoid setting the car on fire.