The question you have to ask yourself is are you willing to pay Shelby prices point for a Track ready Mustang equal to the Z28. I'm only saying this because Ford compromised a lot on the Boss. It was a streetcar that worked pretty good on the track. Same could be said of a Track Pack GT since it's not very far off from a Boss. The Z28 is a track car that can be driven on the street.
The z28 isn't a track car its a collectors car. The big engine and brakes aren't legal is almost all classes. Not to mention who is going to pay close to 100k for a Camaro with a bunch of left over c6 parts. If I was a die hard Chevy guys I'd wait for the new C7Z which will be better looking faster and most likely cheaper.