Carb for 340

Edelbrocks can be a little bigger than needed as the air valve secondary only opens as far as the motor can use. Holleys are a little different but can be manipulated the same way with vacuum secondary springs in the pot. DP carbs with no vacuum pots are generally better for 4sp apps. Check out the Thunder series AVS style edelbrocks or even the Demon TQ clones. They are a bit more adjustable than the AFB. Even a prepped TQ would work great, Demonsizzler can hook you up if he's still around.