Thank you, Wesmamyke. The photo helped me get a clear sense that this is not something to tackle without the specialized tools and parts. Good, that's what I need to know. As the fork is completely tight and functional, I'll simply clean it up, oil the bushings and check out the damper. Oh, and a bit o' polish while I'm at it.
Have you any recollection of the amount of ATF to put in the damper, or even how to determine same?

Added an hour later...
Wesmamyke, your advice was spot on. A search on retrobike.co.uk quickly brought me to high-quality pdfs of the correct manual. And I learned not to lube the bushings, just wash them water, to avoid lubricants, as they will "attract dirt and carry it into the pivot points where it will act as an abrasive". A serious thank you!