All congratulations on the new purchase, Mark; I'm so glad it ended up "in the family" with someone on the Forum where we can follow its progress.
I was "surprised" in a similar way when buying my used 1970 Raleigh Gran Sports 27 years ago. The ad copy sounded great to my sleep-deprived mind (I'd been awake 63 hours with a full load of uni classes and two jobs) and when I went to see it, only the owner's wife was present and knew only that it had been maintained by her husband, "who teaches bike repair at the community college". The bike was parked outdoors in the rain, seemed to have all its major components intact, and had a low price. In that rummy state, I bought it without a test ride.
'Took it home by car only to find many of the spokes had rattled free of the wheels in-transit (semi-laced, not tensioned, and with the nipples barely threaded). That was a harbinger of things to come, but I still have the the frame; everything else was changed over. It rides well with early-'80s Japanese componentry and has been a good, reliable bike ever since.
You seem to have fared much better! It sure looks good in the seller's photos! If it is largely a matter of cleanup and derusting/painting, I'd say you got a real deal. Sometimes, just a little TLC will do wonders in transforming a used bike, and you've got all the most important parts. I'd love to see some photos of it now so we can follow the progress under your ownership. I think it'll come out wonderfully; so glad you got it!
All the best,
Dan. (...who vowed to get more sleep and take a test ride before buying another bike in a rainstorm)