Searching Thos McGrath home

My mother was a McGrath who I believe descended from gr-gr-gr-grandfather Thos McGrath baptized 3 Nov 1813 in Galbally-Aherlow parish.  His parents were Thomas McGrath and Margaret Ryan.  He married Margaret Kelly (per 2 of their children's baptismal records found in same parish), they emigrated to NYC on 1 Mar 1849 with children Thos, James and Anne. Gr-gr-grandfather Thos born 1832 eventually settled in Phila PA area, married Margaret Hynes, had 4 children youngest Dennis born 1868 my gr-grandfather. His son James born in Phila was my grandfather.  Is there any way to locate the hometown/homeplace of Thos born 1813, or his son Thos born 1832?  I have gone as far as I can with Ancestry and the Irish genealogy sites.  Thank you for any assistance.