There was a guy a few years back made a business out of custom parts kits specifically for that bike. Can't remember the name.
At one point they had custom swingarms, but not really cost-effective and not enough demand. Big honking hub motors, DD.
Lots of ways to go, good foundation to start with, used a pannier rig on the top tube for batteries.
Damn, dude had a whole parts list and also many combos he sold. "N" something. over on ES, but this has been several years ago.