I was interested in your posting because I also have ancestors that came from Crosserlough and settled in Taunton in the late 1840's. Do you have death dates, obits or burial sites for Matthew and John?Many of the Irish gravestones are inscribed with a county and parish. The other thought I had was to check for naturalization records. Perhaps you have already checked these items, but if not I'd be happy to keep my eyes open as I poke around Taunton.
My interest is in the surnames Friery, McDonald, Finn, McCaffrey and Gotham.