carb replacement suggestions

Why 800cfm? That seems high. Is your engine naturally aspirated? There is an equation for figuring max cfm. It's CID x Max rpm / 3456 (12 x 12 x 12 x 2), and that's assuming %100 volumetric efficiency. Using the formula, 380 x 5500 / 3456 = 604.74. So, assuming your engine isn't %100 VE, who not go with a 600CFM? Not trying to change your mind or anything, just curious...