G'day Neil
Have a look at this site.
http://www.moss-europe.co.uk/shop/viewproducts.aspx?plateindexID=15506 If you can't find something similar in Australia check to make sure you can import seatbelts before ordering. There may be some regulation that prohibits the import of seat belts that do not have Australian Standards approval. If all else fails get someone to hand carry them for you.
The reels do not look too big or ugly but you would need to see which can be adapted to your car. It depends very much where the secure mounting points are and how the existing belts are mounted. I would not change the existing mounting points without expert advice. I have not seen how the belts are mounted in your car but fixed seatbelts usually have 3 point mounting. For the rear the Type B may be possible and for the front Type A using the existing upper mount as the upper mount/turning point and mounting the reel at floor level. This would need to be mounted securely to the chassis of the car.