How dare you put me in with those Ford and Chevy guys?
I am not a purist, but I think the Cobra should have a very healthy V8 in it. For resale and shows, sure a correct 260/289/427/428 would be ideal. Beyond that it isn't a big deal wht brand is under the hood. They can all make lots of power if you want. Chevy parts are a dime a dozen and that is attractive to lots of people. Personally I wanted a lightweight, powerful roadster that handles relatively well. I liked the looks of the Cobra so that's what I got. Had I to do it all over again, I would get a Ford motor, but only because thats what the JBL is set up for. But then the body/chassis/suspension on those is nothing like the original. Everything is a compromise.