Is a stock bravo one upper case the same as a Bravo XR upper case? Can the internals be swapped from one to the other?

Short answer - no & no

The X cases are larger in the snout where the pinion bearings are housed

You can install an XR upper on any standard B1, 2 or 3 lower

The case is different but you van use XR gears in a standard Bravo Case!

you have to contact max machine worx,they have a new yoke that lets you use the xr gears in a standard case.I did this 13-15yrs ago,and in an old style case no less.