I am rebuilding the original 400 in my 1968 GTO convertible and am trying to decide what to do with the carb. The car is a manual transmission. I have a friend who gave me an 800 cfm Quadrajet 17057274 which is for an automatic 1977 LeMans. I am going to stroke the 400 to a 461 and figured I would need the 800 cfm. Which carb would be best, the original or the other?