Can anyone help me find information that breaks down how many of the Tempest Customs in 1967 had the 326 HO option. I can find only production numbers in general. Does this option add much to the value of the car? The original block is gone, froze/busted and was replaced years ago. I have located a correct motor for the car, but the date stamp is 3 months after the car was built. Is it worth trying to put it back original or invest the money into GTO clone.