Upgrading alternator on '65 Chrysler Newport?

Yup. NO1 main thing to do is run a larger, nice big, not to mention #huge wire, about no8 or 6, depending on the alternator, from the alternator output to the starter relay stud.

Pull the bulkhead connector and inspect it. Jumper the ammeter connectors together.

Then go read the MAD article

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

Don' forget page TWO

http://www.madelectrical.com/electricaltech/amp-gauges2.shtml