As a rule-of-thumb, the limit for turning brake drums is .060" oversize, but some can go larger. Newer drums are often marked with the maximum size; yours might be marked if they have been replaced. The size will be stamped/cast into the open rim of the drum if it is there. Otherwise, you need to know the stock diameter before you can determine if your drums can be turned, and how much they can go. It is not necessary to remove all trace of blemishes from the drum in order for it to be satisfactoy for use- you can turn a drum up to the limit and leave small imperfections/grooves if they don't go completely around the shoe surface. Different shops have different views of what is allowable, and they even make mistakes with their drum gauges. Getting another opinion is a good idea.
Harvester
Unless you get those odd size mid 1980's GM truck shoe sizes. What was up with that??
