Searching for the mysterious Richard Finn

My 2xg grandfather Richard Finn seems to be the invisible man. I have been unable to locate any records for him that remotely match the information he repeatedly gave about himself in New Zealand. 

What I know so far:
A Richard Finn arrived in Auckland, New Zealand on June 29 1865, on the Balaclava. I do not know if this is the correct Richard Finn.

A Richard Finn is recorded in Remuera, Auckland in the NZ Electoral Roll 1880/81, his occupation is listed as Coachman. I assume this is the same person because he married Alice Ann Frost 16 June 1885 at St Benedict's (Catholic) Church, Newton, Auckland, New Zealand and on the marriage register he gives his age as 34yrs, rank as Farmer, Residence as Remuera, birthplace as Ireland and his parents names as Patrick Finn (Farmer) and Mary Finn (formerly Harigan). 

Also in 1885 he had a house fire and the newspaper report states that it was a ten-roomed house, valued at 750 pounds. https://paperspast.natlib.govt.nz/newspapers/NZH18851030.2.21?phrase=2&… This raises the question of how he was able to afford a 10 roomed house the year he got married. Perhaps he was a gold miner? Also curiously he was Irish RC and yet he settled in an area that was 99% Scots protestants, which is a little bizarre for the times.

From this point on his life in New Zealand is well documented, until his death 12 September 1910, at Clevedon, Auckland, New Zealand. His age at death is recorded as 60yrs, putting his date of birth at around 1850. If this is correct then it brings some doubt over whether or not he is the Richard Finn who arrived in 1865, because he would have been 15 years old. This is further confused by his death record in 1910 on which his eldest daughter states he had lived in NZ for 41 years, meaning he arrived about 1869.

In many online family trees the d.o.b. of Mary Harigan has been listed as 1828, and Patrick Finn as 1824, but to the best of my knowledge these dates are not based on any records. 

I have been unable to locate a birth record for Richard Finn, or a marriage record for his parents as he lists them.

I have found a marriage record for Patk Finn & Mary Horgan, 26 Nov 1829, Cloyne, Mourneabbey, Ireland. In 1837 a Pat Finn and Mary Horgan baptised Cat Finn at Iniscarra, Cloyne. I do not know if this is the correct family, but it is the closest I've been able to get to a family that would match any of the details Richard Finn gave. 

I have searched familysearch.org, ancestry.com and findmypast without any success and I'd really appreciate any advice about how to proceed.