I haven't completed such a conversion but I'd recommend a mid-drive for that bike. Probably a Bafang BB0S2 or BBSHD depending on your goals.
I have converted a Specialized Crosstrail Hybrid with a Dillenger rear hub drive. And, while it works fine a mid-drive lets you use the rear wheel drive train as your motor's transmission gears.

You'd have a difficult time finding a hub drive wheel in a kit that accommodates those tires, etc. With a mid-drive you'll keep everything more or less stock except the crankset and any front derailleur, if you have one.

The Fatboy should make a very nice eBike conversion. And, you'll find Bafang mid-drive kits available at lots of places. I'd recommend Luna Cycle, or California eBike or Dillenger bikes but they are stock items available at tons of places.