You know Gerald I’ve been looking in on this and thinking my ‘67 was acting like this and it was the voltage regulator.
Yep! I reckon its the most likely culprit. These solid state VRs do their thing, and while all are very similar, they're NOT identical. My system keeps the battery charged well enough, so I'm not apt to replace my VR just yet. I also keep a 5 W solar panel on the back deck which trickle charges the battery in any kind of decent light. I figure my big Exide battery will be good for one more year's warrant-able service regardless.
These old alternators did well enough for an AM radio, headlights,wipers and an AC/heater blower, IFF the thermo-mech VR they came with was up to par, but it would be chancy if one had to run long on a rainy winter's night. 60 amps is NOT a great margin for comfort even now, with the solid state VR working. I'm looking to upgrade to something capable of 90-120 amps. Several options for this can be had.
I have a couple old square-backs I could rebuild with heavier duty stators and diodes, get a roundback core and do the same with that, or just buy a brand new Powermaster or TuffStuff alternator. One can get either something that still uses an external regulator, or a 1 wire sort, for some more $$$.
Any heavier current alternator WILL REQUIRE HEAVIER WIRING THROUGHOUT THE CHARGING CIRCUITS IN YOUR CAR. I already have SOME provision for a modest increase in current; say, up to 80 amps, but beyond that I will want to go to whatever is suited to the current + 15% over. I always size over by at least 15%, as a good engineering practice.