The 600 will definitely wake the motor up at higher rpms, but you may like the results better of a slightly smaller carb (450 cfm or so) with the stock cam. A stock engine will likely never or only rarely open up the secondaries on a 600.
If you were upgrading now to a bigger lift cam, I would recommend the 600, otherwise go with a 4-bbl with a smaller diameter pair of primary butterflys for better tip-in throttle response. Once the engine reaches about 1600 to 2000 rpm, you won't be able to tell the differece between those carbs. And the Offy is fine also with either carb.
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David
newbie #4153
