For centering, there's not much you can do, unless your kit included
trackbar bracket*, or you have fitted an
adjustable trackbar.
Easiest way to get a rough idea is to measure from the top of the tyre to the spring mount on the front, or to the frame on the back. Then you can decide if it worth the cost to you to buy them. (Assuming the kit didn't come with them already, of course.)
I did the centering myself, initially, then just went for a wheel alignment. Where are you in Sydney? Someone may know of a place that specialises in 4WDs or Jeeps near you.