It lives! After fighting and finally satisfying
the immobilizer, I had to figure out the shift interlock to convince the ECU it was in neutral, even though it wasn't hooked up to the original AT, but instead the MT from the 08 Impreza. Finally got it. With an aftermarket fuel pump and regulator running out of a 5 gallon can, it fired right up.
Now I get to start figuring out pinouts and bypasses to delete the shifter assembly, inhibitor module, brake switch, etc etc.
Have vid but haven't sorted how to do it on this forum yet.