Unlikely for there to be a church record for 1768www.rootsireland.ie
perhaps on www.emeraldancestors.com
Church of Ireland parish registers to 1899 are stored for research in Dublin at the Church of Ireland Representative
Church Library. They do not do research for you it must be done in person or you can have a genealogist get it for you.
There are no census records for this early in Ireland so census substitutes have to be used such as Griffith Valuation but since Fermanagh's wasn't recorded until 1860 its a bit out of range. www.askaboutireland.ie
I answered a James Barton request June 10th. and one of their children's names was Gustavus? Take a look.