Timebandit: I have that very same book coming in the mail right now.
Perithead: Thanks for the feedback. There was some flaky rust removed on one side, and stubborn surface rust on the other. I sanded it all off as best I could without access to a sandblaster, and then coated the whole thing with rust converter primer before I started laying in my filler. Unfortunately, I didn't use good paint when I did that keel job. I didn't have much money (one year out of college, was working at a bank ops center back then). I spent about $300 on fiberglass and filling materials (which felt like a fortune at the time), and had nothing left for real bottom paint or a good epoxy coat. In the end I bought a $4 can of brush-on Rustoleum. I figured that since it was waterproof and sort of rubbery when cured, it would be the best non-marine coating to try out. It's lost its shine, but to this day, it still hasn't flaked off of the fiberlglass--which surprises me.
The keel has moved freely up and down in the trunk since then; no scraping, rubbing, sticking, etc. That pivot hole is what's worrying me. I plan on pulling the bolt before the boat goes back in the water this June, and that should be a good indicator of what's going on in there. Marks or grooves to the outer edges of the bolt would definitely indicate a "wallering" problem on the shaft.
I'm thinking that I'll end up pulling the keel when I pull the boat out of the water at the end of the next season, and spend the fall and winter refurbishing the thing. It's going to take me a while to do it around my job...and I don't want to miss half or more of the boating season...