600 CFM vs 750 CFM...

i can only tell you what i have used for different 340's.I had tuning problems with an Edelbrock 750.I used a 650 Thunder on one 340 and am currently using a manual choke 600 eddy on a 340 .It was easy to change metering rods to get my A/F where i want it and both 600 and 650 ran excellent.