It would be without a doubt Australia's most destructive tornado to date that we know of. Just a pity that BoM does not use it as a guide to severity etc in rating tornadoes in Australia, but I suppose that is due to the fact of what Jimmy stated in a previous post " Seriously, there was a report on the tornado from the Bureau but until the 1990's. Neverthless, the Bureau has not really rated tornadoes until the 1989 Elsmore, NSW tornado to my knowledge."
(I am also curious to know if they have ever rated the Lennox Head tornado from last year, which is another subject.)
Just digging up some links to see what I could find. It is interesting that many sites have the Bulahdelah Tornado in its top 10 of the worlds most destructive tornadoes.
http://watchmojo.com/top-10/geography/
http://scienceray.com/earth-sciences/meteorology/10-most-destructive-tornadoes-from-around-the-world/3/
http://www.islandnet.com/~see/weather/storm/tornadoes-aunzea.htm
Colin