We have to take into account that, generally speaking, a 50-year-old jobbing actor on low-budget TV in 1966 looked a good deal older than a 50-year-old Hollywood actor tends to look now. (Hell, I’m not that far from 50, not Hollywood glam by any stretch, and I still look noticeably younger than my boomer parents did at my age and way younger than my Depression-era grandparents looked at my age.)

Physically, under modern makeup, lighting, and filming, I could see this guy looking very similar in age to Kelley in TOS.