In my opinion, I think the only way to go is a 950HP Holley. I have been told by many carb builders NOT to use a true 850. They explained the reasoning but I cant remember. I guess the 850 is kindof a combination of a 750 and a 950 that generates a weakersignal to the boosters or something. Like I said I dont remember. I would NEVER put a AVS or AFB on that kind of engine. Leave those carbs to daily drivers or classes that REQUIRE their use. Go 950HP, you wont regret. I use PC Carbs in Ontario California. They have built me around 20 carbs in the last 2 years and every one of them runs flawless on the Dyno.