Settings for a bigger rider?

If you're bottoming out set them stiffer, too stiff go the other way. Blaster shocks aren't worth a crap, so don't expect much.
A 400ex on the rear is a big difference. Works for the front is cheapest route. Because you're in OZ shipping is tough.
I usually am against stock Banshee fronts, but in your case I will suggest them.
It all depends on you r budget.
 
I would order a 400ex rear shock with KOR's bushings.

stud spacers on the rear and go for some extended a-arms on the front :)
Not keen on making it wider. It only just gets in my trailer now.

Went for the maiden ride yesterday. Started with front shocks on softest setting and ended up on the third setting. Didn't have the right spanners to adjust the rear shock but it's too soft now. Nail the throttle and rear sags and front lifts way to easy.

The guy I brought it off was 70kg, I'm 98kg, so that might explain some things.
 
If you don't want it wider then you could look into the people that make shock conversion kits. I know Diamond J makes a shock conversion/lowering kit. You can either use it with stock shocks to lower it or put on some yfz450 shocks and stay the same height