Don't think there are any. Wreckers are a business, so they have to keep parts that are in demand. I doubt you'd find any with cars as old as Z's. I hear that when scrap metal prices were high a few years back they crushed all their old cars for scrap.
Best bet is to try Martin Falconer, or keep an eye on the quokka/gumtree for cheap 260Z's or join the WA Z Register email list.