I have been messing around with the adapter plate the last few days. The motor is mounted up to the plate.
All it took was a 2-1/2" hole saw and a few drill bits in the drill press.
The adapter plate is huge. Way too big. I will eventually saw it down for sure and maybe use a chunk of it for a heat sink for the motor controller.
Here is the transmission input shaft with pilot bearing stub:
And here it is after the pilot-bearing-stubectomy, thanks to the cutoff wheel on my die grinder. It took all of about two minutes to complete:
