I was told that I'd have to use a clutch return spring relocation bracket in order to use the 427 z-bar. The 427 z-bar is slightly different to avoid the long tube headers. There is a guy by the name of Bob Bowers that makes new, beefed up, z-bars for the cars. He also makes a relocation bracket. I bought one from him, haven't got the car together to know if it was truly necessary, but I assume it is?