edelbrock to holley conversion

Based on the questions you are asking you don't have a lot of experience with carbs. The Holley double pumper will take a lot more tuning skill to dial in than the vacuum secondary Edelbrock.

IMHO, you would be better off staying with the Edelbrock carb or if you need a new carb going with somthing like a 650 Edelbrock or a Holley 670 Street Avenger carb.