After a few attempts (each involving removal of the gas tank), I think I got the new voltage regulator putting out enough that I read at least 13.6V on the analog volt meter from VDO. Not quite as accurate as a digital voltmeter and it reads 1 volt less than actual due to how it's wired up.
Before the new voltage regulator, it was reading perhaps 13.2V or so.
We'll see how that works out. As I was doing the test rides though, the sunset potential looked pretty good so I switched to Scarlett, my 2014 Ural Patrol for sunset pictures.
Soon after sun went behind the Front Range Mountains
Several minutes after sunset