Jim From T, we have paste solder here that uses Rosin flux, being a technically advanced nation. And we also have decent non-acidic fluxes that can be used for tinning that don't eat the blue. Further, if you talc the bbls above the solder line, it will keep any excess solder from sticking to them. Or you can run a swab of hot steel wool down the groove as you go and that will move any molten solder on down and of the way. I learned all this from Keith Kearcher and Ken Owen, both of whom are well known in doubles circles here and charge less than the figures you quote to relay a rib. To wit "Relay rib - Top - $120.00; Bottom - $95.00; Lump - $50.00"
Now if the blueing is gone, go ahead and make a mess, you have to emery the bbls anyway. But if the blue is good, no need to turn the rib repair into a reblue job.
