Iain,
Recommend you go and buy the book "Monaro Magic" by Norm Darwin. http://www.handpub.com.au/
It has the dimensions of the painted rally panels/stripes including radius of the corners etc in the extensive HQ chapter. The book has an amazing amount of information about not just the HQ but all the Monaro Models. Worth its weight in gold for a Monaro owner.
cheers