example of mine: My car,when I bought the car,ran a best time of 13.9 at 101 mph. All I did was swap in a 750 double pumper for a 600 double pumper and I ran 13.4 at 105.
Also of note,,, 650s/750s/850s used to work better than 600s/700s and 800s. I put a 700 double pumper on a 327 and it was a dog. I got my 750 double pumper off a 283 powered chevy2 I had before I got the Camaro. 600 cfm is not enough for a "good" 350