Edelbrock Performer Carb question

I am contemplating a new Performer carb. 68 Valiant Stock 360(mild cam so I was told but I don't think so ). Stock intake,Doug's headers. I don't see this thing ever going above 5000RPM.
With that in mind would I be better off with a 500 or 600 CFM carb. Just want to cruise it to work and local car events.