Had a similar problem.. Theres a place out wingfield i think it might be ( the name escapes me right now, ill try find it and let u know asap) but its all nissan spares - they actually 'rent' parts to you, for regency inspections etc. A stock steering wheel will cost u $50 to borrow for the day, just go there before regency, borrow the wheel and return it after youre done. U can buy it if u wish, they are pretty cheap.
Same goes for the turbo.. think they do the same with that.
With the cat, i 'borrowed' one from AAA exhaust at richmond - cost me bout $50 and they lent it to me for the day, including fitting and then removing it.
They will go over your whole car, they tested my horn, seatbelts (that they retract properly) etc..
Good luck