Today I am still quite
pleased with the finish they applied, though some rust that was
unknown to me then has recently started to bubble up.

I feel well qualified to comment on this, after all, how many buses have I stripped and repainted? Hell, I can't even remember, must have inhaled too many paint fumes! Anyway, quite a few times I have found rust under what appeared to be a sound area, nice smooth paint without any indication that anything is going on underneath. It lurks under the paint just waiting for the right time to pop out. Bottom line is if you want a perfect paint job and no rust suprizes, strip the whole thing down to bare metal. I've only done this to one bus, the '77 Westy that I did the total color change on-never again, too much work. BTW, while we're talking about rust, I'll mention another pet peeve of mine-the term "surface rust". Last week I patchhed some holes in some drywall, afterwards I rinsed the metal spackling knife and left it to dry. The next day it had some rust spots on it that I was able to wipe away with my fingers-surface rust. But, all too often I see buses listed for sale where the seller says "only has surface rust"-hmmm, can I scratch it off with my fingernail? Highly doubtful. I can tell you from experience, when you start grinding away at this so called "surface rust", you will most likely end up with holes in the metal.   Jeff