Success! This little rifle is pleasing me more each day. Just in from shooting with the redone ribs and here's the results.

A 3/4 inch group of four shots, two right and two left. Both shots from the left barrel went into the same hole - confirmed by recovering all four bullets from the wooden backing. I'm sure this was a fluke as my 49 year-old eyes just aren't THAT good with open sights! Just the same this is close enough for me. Much better than I had hoped for.