Nothing left to do but see if the engine will run.
Once again I enlisted Dale's help, this time to stand fire watch and check for leaks. First we disconnected the top oil cooler hose and filled the cooler with oil per Lycoming SI 1241C. This took about a half-quart and only made a little mess. Then I used the starter to crank the engine with the bottom plugs out until I saw signs of oil pressure. This took three 15-second hits of the starter, and eventually registered about 20 PSI. After a close inspection for leaks, I finally installed and torqued the bottom plugs.
I didn't want to take any chances, so we lassoed the tailwheel to his truck bumper just to be extra sure the plane couldn't go anywhere:
I think the video shows the next events best:
Amazingly, the engine lit after only a few blades, the oil pressure came right up, and it settled down fairly quickly to a smooth idle. In a few minutes' of running I was able to verify that I have a good engine, all engine sensors and gauges are working, both alternators function as intended, both mags check good, and the prop governor can cycle the prop. A really momentous occasion that's been a long time coming. After shutdown, I looked everything over and found no leaks, drips, or wear spots. Later I reviewed the data logs to confirm my in-the-moment observations and found nothing alarming in the numbers.
Then I decided to give the airplane a bath, because in the sunlight it was looking filthy! It's still streaky, but at least it's no longer covered with grime and dust:
