Denby,
Its very hard to find information for those dates in Ireland, even knowing Wexford is not a great help you really need a Townland or Parish. Very few parish registers include those dates, most start somewhat later, but some do include late 1700's.
I have 'Cummins' in my tree, not too far off the name and William was a very commonly used family name by that Family. They were from Ballymurn, Co Wexford but that does not mean anything and even though I know the area I have only been able to get to a possible birth 1776 from a gravestone.
I think you will find Cummins a common name in the south of the County Wexford too. As for Goff/Gough I have not come across that name in the area at all.
Sorry but with that information I think its unlikely that you will trace them.
M