[boxhead]

You mention the body is from WA, but is the chassis from same supplier, or is this "home made"?
If it is a home made chassis, then welding certificates may be required, also torsional and beaming testing, seat mounting, side impact, seat belt mounting etc etc.
If teh chassis was made by teh body supplier, then find out who and if paperwork is supplied, but you also mention it has LS power, I would think that the chassis or part of (engine mounting?) has been modified, this will need to be certified.

If you can speak to any engineers that have been involved, that would be great, even better if teh same engineer is still approving cars and willing to do this one.

Also remember, a common phrase is "80% of the car is about 10% of the cost and time"

Supply more info if you can.