Mine came with a large 2V carb also (Dad wanted it that way), I think this one is rated to flow at about 550 cfm (from the conversations I had with the guys at Holley and The Carb Shop in Palm Springs). It's a holley w/motorcraft tag, with a shelby tag also. When I rebuilt mine years ago, I tried several carbs, the 450 4V with the jets changed (larger), mech secondaries seemed to work better than all the others 4V (though I would have like to try one of those Shelby V4). In the end, I bought a 500 cfm holley, modified it to flow about 550 cfm, enlarged the jets (about 20%) and it really works the best, with the exception of the OEM 2V. That OEM 2V has no doubt great performance, Ford wanted over $100 for the rebuild kit (1986) and I laughed, bought the brand new holley for about $90, another $20 in mods, a little machine work and wa-la! Another reason I proably felt like the engine liked the 2V better is the intake manifold and heads had been hand machined, relieved & matched for the 2V design. The intake runners in my manifold are almost large enough to fit your hand in. My suggestion is, the holley 500 cfm 2V is a very good performance carb, featuring all the goodies you would find on any hipo 4V. There are now some great books out there of how to modify it (simple items) but i would be hesitant to change carbs to a 4V especially if the intake and head ports line up very well. Machine work is probably 2/3 of the power gain an engine gets and if the parts are compatible, why not stay with what works!
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Never trust an over 40 Chevy owner association (They have to cheat to win)
BTW, I ain't no newbee!