How many are using the factory amp meter

So long as you check and spruce up the ammeter, keep the connections tight, and keep the connections good through the bulkhead, and DO NOT go installing a Great Big alternator (less than 50A OK) you are probably fine.

The whole thing with the ammeter and bulkhead connector is a poor setup. Even Ma knew this, and provided "fleet wiring" for 60-65 A optional ammeters

Ammeter construction varies, but on some late pickups, the studs, the ammeter shunt, and the PLASTIC dash mount were all just sandwiched together. As things warmed up from current flow, the plastic would get warm, things would loosen, and then fail.

Rewiring the car so loads like headlights do not go through the ammeter defeats the purpose---this makes it read incorrect. Once you go down that road, with lights, pumps, whatever, you might as well remove it because the readings will be meaningless

Also, this only provides protection WHILE the alternator is "putting out". At slower / idle speeds, the battery will become the supply, and guess what? Current will be going though the ammeter!!!!