Searching for Griffin-Burns 1840's City of Cork

I am searching for information on my great grandfather, John Joseph Griffin, who was born in Cork City in 1844 or 1846. He was RC. His parents (on his death certificate) were Thomas Griffin and Catherine Burns, who I can also find nothing about. His father's occupation was listed as an accountant. I was told by a family member that John Joseph was brought to New Zealand or Australia as a baby by a nursemaid, but this has never been confirmed and I am doubting this very much. He was also thought to be working in the goldfields of Australia in his younger years. He appeared in New Zealand when he married my great grandmother in 1875. Any info much appreciated.