Dear Mr. MacSteaphan,
Thank you for posting your request on History Hub!
We suggest that you review NARA’s Resources for Genealogists, as well as the History Hub Blog titled Suggestions and Advice for Family History Researchers. Also, the FamilySearch Research wiki for South Carolina Genealogy may be useful.
For any records about Roger Gordon while he was in Ulster, we suggest you contact The National Archives of the United Kingdom, Kew, Richmond, Surrey, TW9 4DU, United Kingdom.
Additionally, you may wish to contact the Department of Archives and History for the State of South Carolina as well as the Williamsburg Historical Society for any colonial records they may have about Williamsburg County and its residents.
We hope this is helpful. Best of luck with your research!