Holley 6709 double pumper 750 carb info

holley labled those carbs as an emmission performance carb. they are on a 4150 square bore bolt pattern but are more like a 4165 spread bore carb. they have a 1 9/16 primary throttle blade and a 1 3/4 secondary. they also have the spread bore reverse idle system with different fuel bowls, metering blocks than a standard 4150 carb has. i ran that carb on some stock 340 dusters and road runner back in the day. was a great carb on those stock motors. a plain ol list 4779 750 double pumper is the better carb for what you have in mind.