Direct answer
If the vehicle is registered in the Northern Territory, start at the NT registration pages and search for vehicle standards and modifications. VSB 14 is the national technical code. The Territory decides examinations and accepted evidence.
Distance is not a waiver
Remote use does not retire the standards. If the car will carry NT plates, ask the NT agency how they want a certified modification evidenced — especially if the signatory sits in another jurisdiction.
Next
State rules hub. Check with the NT registration authority before you modify the vehicle.
