Consider that you will need a new carrier for your gears in addition to the Aussie (another $50 or so?) - that puts them within ~$75 of a tru-trac, so I would say that cost is basically a wash.
The locker will make breaking things much more likely. The limited slip will only make breaking things somewhat more likely.
Something else to consider if you have a bit of time. Many 35's had a track-loc (or whatever the stock L/S is) with 3.55 gears (the carrier you need). If you went around the yards, you could probably find one that works okay for cheap ($25-50?) and just run that. That saves you 250-300 dollars that you can then use to buy a real axle (D44, explorer 8.8) when you find one. 8.25 is out since they only go down to 4.56...
FWIW, I think Cutthroat is running a stock limited slip in the rear (8.25) with a front ARB, and he seems to do quite well with that setup.
Travis