Samuel John Preston,Jr.

My great-grandfather was Samuel John Preston, Jr., b July 1836 in Ireland, married to Mary Ann Black b Mar 1842 in Butler Co PA.  Children were James, Sara Jane, Thomas, Margaretta, Olive, Mary Florence, and Ida Pearl.  Sara Jane married Samuel Leopold Moyer, my mother's father.  Can anyone trace Samuel Preston, Sr and his wife Sarah Irwin, both born in Ireland?