Yeah, I was kind of afraid of calibration issues as well, but thought I might be able to compensate through a combination of mixture and jetting changes. Looks like I'll probably nix the idea and tell him he's better off just getting one of those brand new replacement units through Mike's carburetors, this unit:

http://www.carburetor-parts.com/Rochester-1-Barrel-Replacement-Carburetor_p_4411.html

unless there is a better option somebody knows of. My understanding is that the majority of cores you're likely to find for the B carburetors will most probably have similar warpage issues unless you're pretty lucky, and I have little trust for any of the carburetors on ebay. Seems like none of the local part stores other than O'reilly have any availability so that option is out. Recommendations?

Fishing, billiards, trucks, cars, women, in that order.