Did you send in your birfs for cores? The smurfs are not any bigger in flat to flat dimensions. If the birfs used to fit no need to grind any part of the housing. He recommends turning the knuckle stops some though.
I've never seen an aussie locker, but if it keeps the inner axles from going into the diff, leave the clip that keeps it on the birf so if you ever need to change it on the trail, they are easier to separate. Works sort of like a Martack.