Hribman did it, you can check his gallery. It did work and then failed because the stator was off-center. He basically had a steel plate cut and inserted between the flywheel compartment and the stator cover from a KTM, and that's how he could use a Kokusan stator.
I talked to BOSS about it, since he has parts machined for the Berg, like his rad guars, but he did not think it could be financially viable.
Now if you know a good CNC machinist who can precision engineer something, then you are more than welcome, my friend, but overall it would prove more expansive than regularly buyin a new stator every now and then.
Advantage would be more amps and more reliability, plus easier to start pre-04 Bergs.