In researching Doolan surname, you would have to ck the spellings Dulin/Doolin/Dulen/Dooling and maybe even Dolin. As who ever was writing the record, would spell as best they could. There are some sites that have Dulin data. These are under the lines of Dulin/Elgin. The Irish is O'Doolan or O'Dubhlainn,per The Surnames of Ireland by MacLysaght.