Paul,
There are plenty of GT40 guys having 180's made, maybe nose around on www.GT40s.com to get some leads.
You are likely best off getting them made on the car in Australia both from assured fit and $$ perspectives.
FWIW with the heat the ceramic coating is the way to go and stainless gets to look pretty dulled fairly quiickly. My Ultima system is full stainless, the headers are ceramic coated, the mufllers are not and are a dull brown color now.
Julian
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.