Glenn,
They're not real close to you but Gordon Leven in Emu Plains NSW has a good range of 15 inch Avons, I'm pretty confident that someone could probably bring them to Shelbyfest. MT street radials (Drag Radials) are available from Rocket Industries in 255/60/15. I have a couple of near new ones that I'm willing to part with, they haven't been on a track, road only. I wouldn't recommend them for the front though.
http://www.google.com.au/url?sa=t&rc...41018144,d.dGY
Great if you can keep us informed on the rims as I'd be interested in a set of Kidney Beans as well, but maybe blank as I need a Torana bolt pattern.
cheers
Legless