Hi Mark - I'm replying to the group for the benefit of others who may also have an interest or roots in Canton, Ohio like myself.  We're fortunate that the Stark County Court's naturalization records have been digitized, indexed and placed online.  You can find and search them here - http://webnet.starkcountyohio.gov/Clerk_NatSearch/ .  I may have found your grandfather's and will message you privately.

Regards,
Aaron Slotnik
Chicago, IL