Looking for some feedback on carburetor replacement, not an area of expertise for me. My 63 409 has dual Carter Competition Series 625 CFM. I am not sure what if any engine modifications have been made, What I know is that the intake is stock and has Crane Rocker arms (roller).No performance issue’s main goal was to clean things up. Learning the carbs are not original I thought I would replace them with a couple Edlebrock carbs. My concern is oversizing and am looking Edlebrock AVS 500 or 600CFM.