Ammeter bypass

IMHO
You should not have to remove any wires from the stock wiring.

Running a wire directly from alternator to starter relay post that goes to the battery will do the same thing. It also gives you two paths through the bulkhead connector to power the car.

You should add some wire protection (ie fuse/ fusable link etc.) to that wire.

THIS.

and toss the GM one-wire alternator. Keep the stocker. You're making this harder than it needs to be, just to downgrade!