The 1870 census says that the oldest Buckley child, Dennis, was born in Ireland a few years after the youngest Murphy, also named Dennis.
If true, then Michael Timothy Buckley should also be from Cork. Assuming your information about Rose Anna Sweeney's place of birth is correct. Buckleys should be slightly easier to find than Murphys.
1870 Census Franklin Borough, Cambria County
Thimothy Buckley, 56, laborer, born in Ireland, citizen
Rosa Buckley, 56, born in Ireland
Miles Murphy, 24, laborer, born in Ireland, citizen
Dennis Buckley, 23, laborer, born in Ireland, citizen
Thimothy Buckley, 18, laborer, born in Pennsylvania
Mich Buckley, 16, laborer, born in Pennsylvania
Dennis Murphy, 25, laborer, born in Ireland, citizen
Joanna Murphy, 26, at home, born in Ireland
Anna Buckley, 12, born in Pennsylvania
https://www.familysearch.org/ark:/61903/1:1:MZG9-9MCAnd all the males born in Ireland were citizens by 1870. Their declarations of intention to be a citizen, if you can find them, wouldn't give their parents' names, but it might confirm the county of origin.