Craig,
Very possible, this was way before the internet, home computers, etc. -- and living in Dunsmuir (or in Arcata, going to HSU), I was not "in the loop" on any steam loco info, I just remember seeing the locomotive going up the road (northbound)--it could have been anywhere from 1967 to 1976, or even a bit later--I think it was in summertime. It was sometime later when I was told which engine it was--I wasn't even aware of 21 being in McCloud when it was there!
I do remember the SP steam rotary in Dunsmuir around 1966, as it was steamed up in the yard, below the elementary school, and no one would believe me when I said there was a steam something down on the tracks--after all, steam was gone by 1957! It was a few years later when I found out I was right, and not hallucinating.
David D.