From what I have read, Anthony is right.
Miles and the 'Turd' turned the Chevy smiles to frowns once again.
And Zora may have been on the cutting edge of technology back then but the Cobra's improvements were built from the the ground up, on the track. The Cobra was a race car and had gentler versions for the street. The Corvettes were street cars (and the first ones pretty darned lame) that had to be made race ready for the track.
Cobras were home on the track. Corvettes were at home at the Racquet Club parking lot.
rodney