Has anyone tried modifying the 70 Motorcraft 4300 carb for performance? I have a fresh 70 AMX motor, with pocketported heads, free flowing exhaust, and a slightly bigger cam than stock. I have a dyno session coming up, and would love to run a Holley, but am going to try a rebuilt 4300 carb. I cannot find anyone who knows anything about modifying it. How can it be richened up to work with mods to the 390 motor? Drill out the primary jets? How much? Can the secondaries be richened? I have read that these carbs ran lean in stock form for emissions. Can anyone help?