Don't know if your ignition switch has the terminals lettered, on the Kohler 25-099-04 switch which was popular with most of the OEMS using Kohler engines with magneto ignitions like yours, the B+ usually always connects to the "R" terminal on the ignition switch. The constant 12v from the battery connects to the "B" terminal. With the switch in the ON position, you should have continuity between the "B", "R", and "A" terminals. In the START position, you should have continuity between the "B" and "S" terminal. With 42v coming from across both AC leads from the stator, that is the correct voltage from the stator. If the reg/rec is grounded and no output from the B+ lead, I'd say the reg/rec is bad. Hope this helps!