Question on holley 4150

Correct me if wrong but isn't the Holley carb you have one of the new HP series? If so they are jetted real rich right out of the box so it doesn't surprise me to see the A/F ratio where it's at. A buddy of mine just put one on a 406 Chevy with aftermarket heads and a real big cam and Victor intake and it ran real rich. They come with 4.5" power valves so that's about right for you since you said yours runs 8" at idle. I'd jet it down 2 jet sizes front and back and see how it does. May even have to go down 3 sizes. The HP Holley's have 3 jet sizes larger than the regular Holley double pumpers just for reference.