Thanks. Just guessing here but the only difference between 600 and 750 is Venturi size, the throttle bores are most likely the same on both carbs. Someone, perhaps you Tom said that the 500 cfm Holley 2barrel is the same as the front half of a 750. A 1 barrel front half of a 600 would be 211cfm in 2 barrel terms. The same as the mono jet. This could easily be the best of both worlds, a small 1barrel for gas mileage and crisp response in normal driving, with a little more cfm than the 390 when you want power. Jay
