Dougal M, I have a really good pic of your car at the 85 Welly street race, coming out of the hairpin, if you're interested in seeing it. Was this car later painted yellow?
You should speak to David Towe. You'll find his details here. He owns an ex JPS M3 and has a very good knowledge of the 635s and the M3s, and their woven histories.
http://tentenths.com/forum/showthrea...79#post1078079
Check out the 'Historics Awesome Stuff' thread under Australasian Touring Car area on this site.