Would replacing the factory alternator and bypassing the regulator with a 1 wire unit affect the tach and gauges? None of the gauges are working
Gauges and Tach are completely separate circuits from the alternator and regulator.
The only thing they have in common is, they are all electrical devices.
Factory gauges are fed power from the ignition switch.
Factory Tach is wired as in the post above.
Neither have anything to do with the alternator circuit.
Exception if you have a factory in dash Ammeter.