Overcharging

moparker said
I have a 75 shop manual for it. Was gonna get it out today.

Great!
Take some photos anyway.
And then to make it easier on us, a photo of the electrical diagram will help us on this side of the screen. Engine compartment side will be enough to see if more is needed.

moparker said
The guy who tested the alternator was leaning toward the ampmeter or the ignition. Hate to go screwing with either without some sort of smoking gun.

Your thinking a lot more clearly than the guy who tested the alternator.
Follow the schematic in post #26 and you can see the ammeter has nothing to do with alternator producing high voltage.
And while it may relate to the 'ignition' circuit, its not the ignition either. It just happens that the ignition circuit is also the feed circuit for other things that get power when key is in run position.
Besides, we're not 100% sure about how the circuits are wired. If it has something like the optional wiring arrangement that was available starting in '73, or has some spliced feed junctions in the engine compartment like '76, that could change the analysis.