Don't know if this helps, but I have a John McNamara b 1822 Cloonagro, Feakle, Tulla, Co. Clare whose wife was Margaret Walsh/Welsh b abt 1824, Feakle, Co. Clare.
John McNamara (27) and wife Margaret (Welsh/Walsh) (26) and family- Patrick (3) and John (1) travelled to Port Philip, Australia from Co. Clare, Ireland arriving on 26 June 1850 on the Bussorah Merchant (Reel No 2145).
MCNAMARA John, Margaret and family 1850
Ship: Bussorah Merchant Reel No. 2145 Item: 4/4817, p.131
They settled in London Bridge, Burra, Queanbeyan and John's obituary states that he was 'almost first to settle in the district known as Burra, and its development owes a great deal to his foresight and pluck in the years gone by."
Margaret's parents were Michael Walsh/Welsh and Mary O'Loughlin, also of Co.Clare.
From memory I'm sure there was another Walsh on the same ship but it wasn't Margaret's brother as I first thought it could have been.
I got the shipping information off a Victorian Shipping website by chance so you may like to check there as well.
Happy hunting,
Robyn