The carb was missing the throttle stop screw spring. This was bugging me, and I couldn't find one on the Internet. So I made one out of an old ballpoint pen spring. I had to cut it in half and increase the diameter by stretching it in steps over a series of Phillips screwdrivers, but it works.

I also used the instructions from 52Merc to easily convert my oil bath air cleaner to use a Fram CA568. Thanks again for that tip!

Oh, and I rethreaded the post so the air cleaner lid could be tightened down and the incessant rattling is gone.

And I got lucky and adjusted (tuned) the right horn so it works now. It wasn't working before now, and I thought it was bad until I saw the adjustment in the Shop Manual and decided to try it.