IT RUNS!
Long post warning:
Turns out there's a tan/black and tan twisted wire pair that run though the entire car. It's a serial communications wire of some sort. Basically it starts at the OBD2 port, goes to the power stearing, comes out of the power steering (as brown/white and brown twisted pair) then goes from there into a blue and white connector on the BCM.
It then exits the BCM out the same connector as tan/black & tan twisted pair...
View attachment 556
(The wires with the stripped ends)
...into the main connector, which is the one that has a white lever and gets cut out and the 7.5' extension. I did not cut my connector out, just extended one side.
Here's the important part: from that main connector the tan twisted pair goes into a "Continental" transceiver of some sort which is located in the center of the back deck below the rear glass.
Knowing I wouldn't be using this Continental box I cut it out.
As it turns out, the tan twisted pair (that I cut out) goes from the Continental box to the ECU. By removing that those wires I disrupted communication from the BCM to the ECU, hence the no start.
You can test this by checking pins 43 & 44 of the #1 ECU connector plug. They should have continuity with the original tan twisted pair at the OBD2 DLC plug.
View attachment 557
Mine did not. So I ran a jumper wire from the BCM blue and white connector (see first photo) to the main-harness-to-engine-harness plug, which is where the continental transceiver wire was originally cut out from.
View attachment 558
(Two cut wires bottom of photo)
This reestabilshed communications, and it started. As a quick check for anyone else, my fuel gauge now works and it didn't before.
One final note: the clutch position switch is a potentiometer. The car will not start if it is fully open OR CLOSED. I thought I was being smart by popping the switch off the clutch pedal and taping it closed so I wouldn't have to deal with the pedal, but this does not work. The switch must be in just the right position to allow the car to start.
The question is now how should future builders deal with this. I think, (but can't confirm) that one could cut the plug off the continental box and simply connect the four wires together, tan to tan and tan/blk to tan/blk, obviously, and everything should then work.
Special thanks to Lonny who provided spectacular support, staying up late and sending me pictures from their factory service manual. He's the one that suggested the problem was with the communication wire pair and saved me a lot of time.[/QUOTE