Larry, A wiring diagram in the '68 Service Manual shows the breaker.
I looked there but couldn't find it there. Although, the way the stuff is organized it is not surprising. Anyway, assuming 30 amps is the right number, then I would jumper directly to the motor with a 30 amp fuse. You'll want to disconnect the wiring to the motor and power it directly. That way, the only component being tested is the motor itself. If you blow the fuse, then you know the answer. Remember, these motors are almost 50 years old, so having some shorted windings is not all that unexpected.