I found your original post interesting. David Gibbons and Mary Ann Moran Gibbons are my 3rd great grandparents. I live in Utah, United States but i am originally from Pennsylvania where the Gibbons family (children). Some of my records indicate that the children were born in Westport. I don't know if that means anything to you but I did want to connect with you in case you find anything about the family.
I have no sources for David but I have his death year in Ireland as 1859. I believe some of his children, mainly sons, headed for USA around 1855.
I do have a short history of the family (David and Mary Ann) found in a book written in 1907 and it states that David was from the clan of ship builders that might still be in business today?
I also believe the Gibbons family was Roman Catholic. Their grandson, son of Thomas and Anna Reynolds, became a Catholic priest and was very well respected, died in 1916, in St. Paul, Ramsey County, Minnesota, USA.
I like to keep in touch with you in case you learn anything new of the family. I could send you family group sheets for the descendants of David and Mary Ann if you are interested.
Thank you for your time.
Carol Brennan Moss
P.s. My Brennans are from County Mayo too, near Charlestown. :)