Be aware the generators come in 2 circuit types, A circuit and B circuit. The 2 are not interchangeable, and test differently.
Lol at the bad of the vreg. If it has a single bias resistor between the field tab and ground, it is A circuit. If it has a bias resistor between armature and field, it is B circuit. B circuit vregs may have a second bias resistor present. Naa are b circuit.
In general, polarity reversals on genny systems tend to weld field contacts, so you see high charge rates, thought could have damaged the cutout.
Standard testing involves jumpering out the cutout, is, arm to bat, if nothing, then full field while jumpers cut out.
B circuit full field jumping bat to field.
A circuit full field jumping field to ground.
See what you have before testing. A circuit was very popular before the 50's
Post back if you need help.