i dont know about paper work for interstate cars as ive never bought one from interstate before but in terms of your cars modifications and appearace, i would try to make it look as stock as possible. since yours has ap racing brakes, sounds failry modded. although i have a friend who bought his car in a modded condition and got it registered and all the necessary paperwork done in whyalla (i think). give ice_duck a pm as he was the guy im referring to.