I believe what you will find is that "whatever" grinder you choose will do one of two things. Weld that one really bad lobe up and regrind the cam or they will swap you a better core. That one lobe I don't believe can be reground.
Seconded. Most of the material removed from a regrind is off the base circle to increase the lift, not from the snout of the lobe. Thats why longer pushrods are sometimes needed depending upon how much is cut.