Charging problems

Excellent. That is the solid-state Vreg for 1960's systems I was talking about. I like the small shiny flat-pack. You can buy them as a larger black box to look like the original, but the covers vary slightly. Some people re-use their original covers for exact OE look.

Trouble-shooting is same deal as post #4. Vreg strives to maintain ~14.3 V between its case to its IGN terminal. It does this by commanding "more" or "less" output from the alternator by controlling its field current (Kit Carlson says it switches on & off rapidly, which you can see on an O-scope). If you insure there is minimal voltage drop from its case to BAT- and from BAT+ to its IGN terminal, then you should measure close to 14.3 V across the battery posts when idling fast. You can buy a cigarette-lighter voltmeter to monitor while driving. 14.3 V will charge the battery, but not over-charge it to where the water dissociates into O2 & H2 (explosive). With car off, a good and charged lead-acid battery should measure ~12.6 V (not sure about Optima gell type).

Your 1960's type Vreg applies a positive voltage to one field terminal, with the other terminal grounded. Doesn't matter which is which, but insure one is truly grounded and that the Vreg "FLD" wire goes to the other terminal. Early alternators had only one field terminal. There was no spade to connect to on the other brush and its gnd connection was just by having no insulator between the brush and alternator case. But, that is aluminum which corrodes and aluminum oxide (white powder, "alumina") is a poor conductor. Of course, you can use a later square-back alternator w/ 2 terminals. Simply ground one of them. Sand away the white powder first and coat w/ silicone grease, and/or run a dedicated ground wire to a solid ground (as most new cars are wired).