A few days ago, I took some soap and the garden hose to the chassis of this set. Cleaned up pretty good. There is a little bit of rust around the rear edges, but not bad.
Today I decided to try giving the chassis its first taste of electricity in 28 years. I put in about a dozen tubes, and then went through the long painful process of slowly raising the power to it. After a few hours of increasing the voltage bit by bit (and so far no bad surprises), I connected a wire for an antenna and a test speaker. Hey! We got some sound going on here!
I was able to tune in the local stations pretty good. I let it run this way for about an hour. No smoke, no sparks, no hot parts.
I did notice that the first IF tube had a noticeable increase in brightness when I would put the tuner on channel 4. Not exactly enough to light up a room, but just enough to say "hey, that's odd!" Swapping it out with another 6BZ6 cured that.
So far, the only thing noticeable is that the flyback has had some work done on it. Looks like some of the leads were changed, and looks like a little bit of wax dripped from it. Doesn't look too bad... I've seen far worse. There is also the fact that there were 3 loose damper tubes rolling around in the cabinet. For now, I will put this on the list of possible failures (although it may turn out to be good).