Sorry forgot to mention the wheels. They are from MG Models - I ordered them from Icaro (
http://www.icarohobbies.com/) and just sent them an email telling them what car I was doing (total was about £13 ($24-ish) inc p&p). The wheels came ready made up and just needed the stub axles modifying a little to adapt them.
Only changes to the body were to take off the Pininfarina plinths on the wings, alter the front and rear valances to remove the bumper mountings and scratch a quick release filler.
p.s. I believe Testors do (or did) this kit - I got this one via ebay from Germany and have never seen another apart from a built street version on another forum.