I ran three 250 CFM Holleys with a homemade linkage setup for almost a decade. The throttle response was incredible, the best I have ever had on a carbureted car. Basically it was a 750 CFM triple-pumper... Downsides were around town fuel mileage and top end power due to the 750 CFM limit... 13.6s@ 102 MPH. The carbs were meant for a 289 Cobra, and bought new at a swap meet in Houston for $40/set of three. On the end carbs, I had to cut down the extended air horns to clear the cross bars n the air cleaners.

Here's a photo of the setup: