To keep my sanity, and a sense of progress, I was continuing to clean bits and pieces of the bike. Did not want to remove the jugs, etc, and was trying to figure out how to clean up the blossoming oxidation of neglect.
Tried a drill-mounted wire brush, couldn't get down into the spaces very well. Skinny little wire brushes were too aggressive and removed the patina. So, I ended up with what I think worked out well: I fold a green scotchbrite pad lengthwise, and pulled it down into the fins while running back and forth. Lots of cruddy dust later, I sprayed it all with WD40.
Photo shows front cover (done on the bench wire wheel), the cylinder on the left of the photo has been cleaned with scotchbrite per above, the one on the right is how it started. A dramatic difference!