I just redid a top rib on a Meffert drilling today. A little nerve-racking because if you overheat the bbls the side ribs come off and then you have three ribs to deal with, all at the same time. My comment on this thread is
1. I see rust about 50% of the time under loose ribs.
2. Most of the work is setup (cleaning, tinning, nailing the ribs etc.) Running your torch down the bbl and feeding in some addl solder doesn't take much time at all. Thus I don't think you save a whole lot of time but doing a partial job, and you surely gain a lot of peace of mind by doing the whole rib.
3. If you apply talc to the bbls and sides of the rib, and if you use a decent paste flux and apply it precisely, there isn't much cleanup required. A little steel wool in a hemostat will clean most of it up before it hardens.
