you can buy alienbees in Australia, however they are more expensive.
https://paulcbuff.com.au/cms/ I have experience only with their USA Customer Service, and they were very good. I'm using B1600 and B800
what you may find interesting is output test for different light modifiers. (check last position on the drop down list)
also check their PLM system http://www.paulcbuff.com/plm.php even if won't use their lights
the biggest one is really huge but all very light and priced very good and with front diffuser give very even light across
I'm using Soft Silver but for your output requirements you may need extreme silver.
much more efficient than soft boxes based on my experience