How many are using the factory amp meter

Ammeters are from an age when drivers actually knew how their cars worked and having the gauge told them when and if something malfunctioned. Voltmeters are useful but much more of the age of idiot lights that tell you something is wrong way after the horse has left the barn and the damage is done. If you fear the original gauge, you can always get a new ammeter, and you can run the wire through a grommet in the firewall, not the bulkhead connector - that way you can still use the connector as was intended for the other dozen wires in the system.

My 2 cents...