Frame arrived this afternoon. I'm going to spend part of Friday cleaning it.
All I did today was measure was was formerly the engine compartment in order to develop a plan for the battery rack and motor mount. And thankfully I've figure out how to fit everything in there with room to spare and only minimal cutting of the existing frame.
My preferred battery setup means I have to add a chain drive axle. This affords me more flexibility in gear ratios and the option of later changing the wheel size (in diameter and width) if I want more ground clearance.
The extra appeal to mounting everything in the original engine location is that all of the working components will be visible, and easily accessible for maintenance.
Money spent so far: $130