John Downey b 1811/12 Dublin

My grgrgrandfather put on his children' birth certs that he was born in Dublin but where?. He came to NSW Australia on the "Templar" 1844 ? as a shepherd/ farm labourer and worked in the Murrumbidgee area  around Yass, Gundagai and Wagga Wagga. He was working at Darbarla near gundagai on the Murrumbidgee River when he married Bridget Reynolds who was 16 or 17 and had just come on the "Thomas Arbuthnot" in Nov 1850. She was employed by a Mr Peter Ross for 12months as a house servant. John worked on properties name "Kimo, Newtown, Wantabadgery and Mittagang" and had 11 children. He was Roman Catholic and dont think that he could read or write. My Aunty tells me that he was the "black sheep" of the family and was sent to NSW as a "remittance man" and used to receive cheques from family in Ireland. When Joh and Bridget's twins were born in 1872 he stated that he was born in 1811 and in Dublin.

Does anyone know anymore?