Looking for Luke Casey b. abt 1833

I am trying to find information on my great-great-grandfather Luke Casey.  Oral history said he was from Co. Tipperary.  He emigrated to Buffalo, New York in 1847 (most certainly through Canada).  He was in Cincinnati, Ohio by 1849 where he met and married Ellen McCormick/McCormack who was supposed to have been from Co. Limerick.  On the marriage record in 1852, Luke was recorded as Hughonis Casey.  We don't know anything about siblings or town or parrish, etc., unfortunately.  He was a Roman Catholic laborer.  

According to the cemetery record, they listed his parents as Mark and Elizabeth, but we're not sure how reliable that information is.  

No Luke Casey found in Tipperary North heritage center nor Limerick Ancestry.  “A” Luke Casey found in Mitchelstown Parish, Co. Cork, baptized 12/01/1829.  Parents were Patrick Casey and Ellen Ryan, Witnesses:  Timothy Twomey and Bridget Harkan.   We don't know if this is a match.   

Attached is Luke's Declaration of Intention to become an American.

Any help would be most appreciated.  Thanks!