Look into replacing the regulator. It is that important. A Bosch type relay supplying full-bore battery power to the alternator field, plus powering the IGN terminal of the 8313 voltage regulator commonly raised potential charging amperage of the MoPar alternator from the lower 50's into the 60's. MoPar made a 78 amp version of your alternator (call it a "78-amp squareback") that charges much better at idle as well as high speed. It is a clone of your present alternator so bolt-for-bolt and wire-for-wire, it is a direct replacement for your present alternator.
Look at your alternator. See the inch wide steel stator lamination, that rings the outside of the alternator separating both case halves?
The 78-amp alternator in auto parts store catalogs is known as a "LESTER 7024"