Looking for John Keenan information

In researching my Great Grandfather, John Keenan, I have found the following: His US Naturalization record indicates he was from County Down. I also have what may be his Baptism record. The following is what I know from these sources:

His fathers name was Patrick Keenan, and his mother's Mary, although her name on other US records is listed as Ellen.

John was born about 1928.

The Baptism record I have indicates he was baptized in Newry on 22 October 1830, his father Patrick, mother Mary, and sponsors Charles Courtly and Mary Farmer.

His wife was Bridget Castles. I don't know if they were married in Ireland, or how they came to the States. The natualization record states he arrived in Boston in 1848.

Would appreciate corroboration of the Irish data and/or any other info that might be available.