Coming in a bit late to this party but just for interests sake, I have Corbetts in my tree in the Ballarat area but I they don't seem to match up with yours ... (?)
James Corbett b.1818; Ireland m. 1846 in Geelong to Ellen Croak.
They had 9 children, mostly born in Geelong & Creswick (outside of Ballarat) including John b. 1853, however he married Catherine Annie Wood and had 12 children (with no James').
However, James Corbett b.1818 immigrated to Australia with his 2 brothers, David (who had a son John b. 1839, I'm unsure who he married) & John (and their wives), their progeny is extensive with a very many Davids, James & Johns so chances are, we are related!