Hi Dave and welcome to the forum.
Here is how I would do it.
Do a suspension lift,most of the aussie kits will get you 2-3 inches above standard height.
This will enable you to run 33 or maybe 34 inch tyres without spacers or a body lift and it will keep you legal in most states(NSW are about to bring a 2in max law)
The other reason not to run 35 is that the BJ73 will be struggling to turn them ,even with a turbo.
To correct that,it would need regearing the diffs or the t/case.
I think you will find that keeping it simple will still get you 98% or more of the places the big boys go without a $7K price tag.
Good supple suspension that can flex over obstacles and allow lots of travel are the most important requirements.
When I did the lift on my 73 series ,it was already sagging at least 2 inches.
So when the new springs lifted it 2 1/2inches above normal + the sag and adding the 33 on the same day,I got 5 inches above what it was.
Good luck with the Army training