Tell me. Have you done any 1940 census research for this name. The Nat'l archives site is free and will allow you to search on Ancestry all of the counties in SC or any other state. I have seen the name John Henry while searching. I can't remember which county but my area of researching is Edgefield and Laurens. You will have to basically need to look into all of the 'townships' as well as towns and city. I remember the name because I was looking for a gruncle who's first name was Henry and my grandfather's name was John Henry Adams from MS. It's there just time consumming to find.
Make sure you look into getting the 1930 ED#. the 1940 ED# may not be the same.