volt gauge or not?

A '65 A-body may only be pulling 30-40 amps max. Those amps may have to go through the bulkhead connector. Age and corrosion may add resistance to the bladed connection at the bulkhead, causing heat and possibly melting. The amperage passing though this connector is passing through the ammeter. Higher amp draw might be put on the system, i.e. the suspected connector and amp gauge. Over time the wiring, larger alternator, additional electrical devices may be added to the system, and it would be a matter of the wiring and both the bulkhead connector and the ammeter to handle these loads. The voltmeter would not be in series and exposed to the full system load. It would be good to know at what loads the factory set-up may fail or overheat, 55- 60 amps etc. when discussing options.