[rdorman]

I would say it is probably not worth spending the money. I recently read a test of a engine of similar cubes putting out about 460 ft lbs where they tested Holley carbs from 390 to 1000 cfm on the same motor. After getting the AF correct, there was very little difference between 600 and 1000 cfm in terms of power. The difference between the 600 and the 750 was only an average of 1 ft lb and hp with the peaks being the same. So you may see gains, but I would not expect much.... at least not enough for me to change the carb. The stronger signal of the smaller carb may be better at the engine speeds and loads that you run most of the time. Now if I didn't already have the 600 on the motor and tuned... it would be a different story!