After a generous sanding with 100, and then 150 grit, I applied two coats of hot, thinned tung oil to seal the wood.
The finish really doesn't show in the pictures because it has almost no gloss (the way I like it), but the wood is smooth as silk:





And of course the requisite powder can:

While I had the barrel off, I closed off the vent with a piece of fuse and filled the chamber to the top, as near as I could tell, with Goex FFFg. The charge weighed 2.9 grains on my digital scale. The chamber might have held a smidgen more, but I kept overfilling it and having to dump it it and try again.
The smallest dipper in my Lee set is
.3cc. The chart says that it should throw 4.8 grains of FFFg, but weighed on my scale it only averages about 4.1 and that overfills the chamber. I'm going to try to make a copper dipper that throws a consistent 3 grains.