I personally think that Chevy-powered Cobras are heresy. I mean, Chevrolet had their chance to power the snakes in late '62, but Zora and the other bow-tie execs told poor Carroll to pi$$ off.
Please don't sacrifice a perfectly good SPF or ERA with a brand-x powerplant. Instead, get yourself a "COBRETTE". Here's the link:
http://www.vipercarparts.com/kits.html