GCS is an unknown chip but collectors have put several names to the initials including the KY boys. None can be verified.

The OC chips were Delivered to J Barnett, Jerome Hotel, Hammond. IL 1940 - 1957.

It was a mail drop address for
Owl Club
Calumet City, IL

Big illegal. The chip delivery record is in the Taylor records on Preserving Gaming History.
http://www.preservinggaminghistory.com/