A vacuum secondary carb will be more driveable right out of the box than any other type. A 600cfm will give decent power and 20+ mpg in 5th gear. A 750cfm will give +30 more horses, and your mileage will drop 2-4 mpg. Depending on what stock carb you now have, (spreadbore or not), a new carb may not bolt onto your stock intake, forcing you to change intakes. Both Holley and Edelbrock make good carbs for your use, although the Holley is the more popular and better understood. They are priced similarly, too.
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