As an enthusiast, I'm sure you'll find this history interesting too.
http://www.gracesguide.co.uk/wiki/A_Shipbuilding_History._1750-1932_%28Alexander_Stephen_and_Sons%29:_Chapter_1
Now to put a cat amongst the pigeons= is your initial information on the fate of Otago correct? One online source states Otago was sold to Portugese interests and sunk in WWI, but most sources imply she was hulked in Australia. This can be explained becayuse there was actually another ship built by Clyde Shipbuilders Robert Duncan Co in 1869, also called Otago. See here; http://www.clydesite.co.uk/clydebuilt/shipview.asp
I'm sure subsequent historians have got these two vessels confused:
The Otago built by Robert Duncan co in 1869 was sister to James Nicol Fleming. I found a photo of James Nicol Fleming (renamed Napier) here http://www.clydesite.co.uk/clydebuilt/viewship.asp?id=16842. She is very clearly a very large ship rigged vessel with obvious features such as a turtleback deck.
To reinforce this further, all the pictures of (Alexander Stephen) Otago as a hulk in Tasmania conform closely to an iron clipper of 364t. http://www.parks.tas.gov.au/index.aspx?base=1793
good luck in your search.
Will