Answered my own question, looks like they are exactly the same with the exception of minor differences in the wiring. The pigtail is longer on the 650R's stator and the AC coil leads are male connectors. Easy fix.
The 400 is getting a refirb over the winter. VG seals were shot so I did the topend, went through the rest of the bike, greased everything. I'm getting readt to revalve/respring the forks and add a few watts to the electrical system.
Amazing what some plastics will do.
Engine sidecovers are at the powder coaters.
We have a 3 day 450mi offroad ride coming up in May, it circles Canyonlands NP which is pretty much the middle of BFE around here. I'm planning on taking the XR4, great mileage, uber reliable.