I earlier posted though that if the customer wants to take care of that re-marking themselves, Jess will leave it alone. There are no markings on my Springfields' barrels and there's an outfit in town that does nice engraving that I'm going to have mark the caliber. Jess said that's fine and he won't mark the barrel.
If someone wanted to have "30-06" milled off and "35 Whelen" (or whatever) re-engraved on that new pretty flat, I'm sure he'd let you do that - why not, saves him work and time.
I just did an image search to try to find an example and couldn't, though I have seen it done and it can really turn out pretty nice.