I have a 66 cpe and am using a holley 600cfm carb. It runs pretty good except for 2 things. First is from a complete stop if you accelerate fast there is a slight hesitation. Second when you park it in the garage and come out a little later the garage smells pretty strong like gas. I thought this was normal till a buddy of mine installed a different holley carb on mine temporarily and both problems weren't there anymore.