there are many brake upgrade threads for AU`s, i had a bit of a squiz but eyes are startin to fail me
,you`ll probably find the info here if your eyes can hold out ;).
hoppers stoppers a while ago had brackets for their own brake upgrade kit for Au`s, i had quick look a few mins ago there`s no listing of it on their site that i can see, but they still might be able to help you, worth a phone call perhaps.