Great, thanks for the pics. Would you think it might be possible to put the internals of the BT inside a regular Pro 2? I'm thinking it should be possible.
Here are the pics:
Sorry it's rotated on the pic, but well, looks like keyswitch boards match. So yeah apparently it's possible. But I'm not sure, haven't tried yet (it would need unscrewing 18 screws, to me it's fine as is). Maybe Hasu. Or maybe when I'd feel the urge to dentalband it (I don't really want to do that now, but it rattles as a mother****er, same as a stock Pro 2). Controllers are entirely different though, and probably different voltage. It's not that ugly to ***** about it, but yeah, there's no white or Type-S HHKB BT (yet?).
Upd: long story short - you can't put HHKB BT internals into a HHKB Pro 2 case without damaging it (I'll post pics later). Sorry for raining on your parade. You'd either need an extender cable for the bluetooth board or cut part of the left leg compartment off. Also the keyswitch board blocks the top left screw and there's a few plastic stems (at least 2 long ones at the top and 1 at the top left screw) that you'd have to cut off, irreversibly damaging the case.
Upd2: more pics - you have to cut off a few plastic stems and probably use an extension 20 pin cable because bluetooth board interferes with the left stand (you probably won't cut the case so much, all I've done is pretty innocent. Warning! Gore!).
TL;DR: I wasn't able to swap cases, it needs a lot of carving (more than I can allow in order to sell the HHKB Pro 2 afterwards). Maybe it's possible with a flat 20 pin extension cord to move the bluetooth board out of the way (you can actually close the case if you move those boards a bit here and there. Not sure about the battery though, probably you could find a place for a small Li-Po battery (it's not that notorious power hog anymore) and a tiny charger board. There's no place for 2xAA, that's for sure.
P.S. That hump with batteries is actually removable, so one could probably mold another, a more pleasant one. The shape is pretty complicated though.