Teardown of the car is continuing, albeit a little bit slowly.
The heater core is now gone, and I’ve completely de-wired the car. Dash bar is gone, and so the only bit left to remove is the steering wheel support and the padding/heat shielding behind it.
Next comes removing the BCM and all associated wiring from the car to simplify the wiring as much as possible. All that really remains is the dash connector, accelerator pedal, brake light switch, and the OBDII port. Just about everything else NOT in the PCM harness goes away.
Will see if this car will actually start when it all goes back together…