Ok now that you mention all that, the engine will need a large carb. CFM rating goes off engine size and max rpm. Its also dictated by intake type and whether you want to drive it on the street. From calculating with 85% VE and a single plane intake, the engine will need 855 to 1015 CFMs. So though way at the bottom, the 850 will run that engine to 9000 rpms. The 1050 he was talking about would have been better for power and top end than an 850. An engine hitting 9k is going to need a lot of air, and a large cfm carb has large openings that wont act as a bottleneck for all that air, but lower end will suck bad. Its like trying to use a garden hose as a straw for your drink. Would have to have some good lungs to do that.