Sounds like maybe you're working with Highway 61,,,which builds very high quality and detailed 1:18 scale cars. I have several of their pieces, including Mopars, Sox's '70 Cuda, and many '69 Camaros which are nicely done, like the Jenkins car. As far as Cobra Jet Mustangs,,they're out there, I have Hubert Platt's Tasca Ford sponsored '68 Winternationals Mustang. They've also recently come out with some beautiful 66-67 Oldsmobile 442s, and their "Hurst Hairy Olds" is incredible. I recently picked up a '65 Plymouth "Melrose Missle" altered wheelbase car and was fortunate enough to run into Cecil Yother and had him autograph it.
One of my favorite websites for 1:18 scale cars is
www.supercar1.com check it out if you get a chance.
Danny Durham