alternator upgrade and gauge help

This question has been posted and answered about a gazillion times. If your battery is not running down, your alternator is doing its job. Your car should run fine for over an hour just off the battery. Your problem is corroded connectors in the wiring, particularly the bulkhead connector. Just upping the alternator might fry your wires and ammeter.

My 65 Newport still has the factory round-back alternator (30A?) and I have TBI w/ electric fuel pump and AC. My battery only ran down once and I found one of the 3 alternator diodes had failed, curtailing its output. That was 10 yrs ago and I was driving it daily last year, with multiple short trips per day. I don't have monster speakers, just a 50 W stereo.