Had the same thing happen to me. Was lashing the valves and was holding the feeler gauges. One for exhaust and one for intake. Was checking my exhaust valve right behing the alternator and managed to stick the second feeler gauge into the back of the alternator. Pop! No power anywhere. Fusible link was fine. Got under the dash move a bunch of wires around and noticed I had interior lights again. I have already bypassed the main power by the bulkhead connector. I’m sure its on the amnmeter posts.