"Normally" the regulator/rectifier pack is the failure point in most motorcycle charging systems. It is simply reassuring to know if there is a voltage test for the stator/rotor output that would eliminate any doubt about the health of the coils in the stator. A resistance test is fine, but nothing would beat a voltage output check.
At this point, I'd go ahead and get a new R/R pack, and see what you get.
