I have a 326 with a Edelbrock Performer Intake and a Carter AFB Comp series, it's the same as a edelbrock performer carb. I have a spacer it's a 1/4" and there is a little more space, I'll try to measure tomorrow.
You know they do make drop base Air Cleaners? I just found out about them. if it's not stock and a show car you can use this if space is a problem.