In short, It works. I actually meant to post this in August, but forgot.
Here's the pre-debug final assembly
The thumb lever is a touch far away, but still comfortable to use.
The drive side. We never actually did anything to attach the small pulley to the motor sprocket. It's just a taper press fit. We'll pin it if it has trouble, but it works so far after a few trips.
a view of the fender washer mounting method
Brian taking it out for a spin. He had some trouble, and we ended up moving the motor assembly closer to the seat to gain a small amount of tension in the chain.
The new motor position.
I don't think ther've been many problems since the last adjustment
It was alot of fun to tool around.
All in all, a good finished project. Good thing too, since I promised to buy it if it didn't work.
If I were to do this again, I might get a bigger battery pack, though range doesn't seem to be a problem. Also, Try not to have bolt heads intersecting with the chain. It doesn't work that way.