Quite a few options on eBay locally for the ball joints but I can't speak for quality. Berry motors in Mitcham can sell you a re-conditioned steering rack. Otherwise I believe there is a place in Dandenong South that specialise in steering racks. Check out this link:
http://www.nationalpowersteering.com.au/
I saw a listing for a steering rack for 740 about $340 on their eBay account a month ago