Mark, try Wayne Hennig of Noosa Cats boat building fame here in Queensland.
He has several Porsche Cup racing cars that he strips for this purpose. I have heard he may have a couple of spare RHD interiors from totalled cars.
http://www.noosacat.com.au
You could also try
http://www.swanporsche.com.au
or
http://www.aporschapart.com
Or if all else fails have a good trimmer custom make them using your old ones as a template.
How did you go organising a local p-car run?