Double Pump vs. Standard.... Good? Why?

On a mildly warmed over 318, we have an Edelbrock Performer Intake and Carb setup, installed before we purchased the car.......the carb was without a proper choke, so we replaced the entire Carb with a new 1400 series Edelbrock Performer Carb (forget the actual number) and electronic choke.

The car just does not seem to really "get up and go" from a standing start............ I've drag raced 2 BBL Mopars in stock eliminator with better starts, to be honest.

I'm sure we could get better results if we took it in for a professional adjustment and dyno testing, BUT I've read lately that a good "double-pumper" would be MUCH better for this motor than the standard style Edelbrock we have, and especially for the rapid response I'd like to achieve off the line.

Could someone elaborate a bit on the differences between a double-pumper and a "non", and what benefits there would be...........and how about overall mileage when making such a swap...........what size CFM for a mild 318?

We appreciate the input.