Better late than never... there were 27 P4's officially imported in Australia with 29 actually built. Not sure what happened to the other two, but I heard a rumour that one fell off the dock!
I know of 7 P4's confirmed running today, I have been told there is another in SA (white), however I haven't been able to confirm this yet. If yours is still running, then that's 9 accounted for. I know 2 confirmed wrecks. I have seen 2 complete sets of P4 running gear for sale and another viscous coupling kicking about, so that's at least 5 that are definitely gone.
I'd be very surprised if there are much more than 10 still on-the-road.
If you do happen to have any information on the whereabouts of any P4's, message me and let me know.