If your current alternator is functional (sounds like it is) I would suggest just run it. Don't do anything to it.

As mentioned, parts house re-builds of 40 YO alternators leave a lot to be desired. An old alternator can only be freshened so many times and still work reliably.

A later squareback at 78 amps would have more output but do you need it? A Powermaster squareback would have even more amps and good chance it is reliable.

The weak link in the factory system is the connections. Bulkhead connector is top of the list. It overheats and melts. Ammeter conections next (if applicable) and small gauge factory wiring last on the list.

If you upgrade the alternator or even if you don't, suggest you use one of the many options to bypass and/or fix the weak spots in the OE system.