RPM airgap with carb spacer?

Hey guys,

Im currently running a stock edelbrock RPM air gap manifold. With me new 360 build in order to keep costs down i was planning on reusing it. Im going with a hydro roller cam, so im going to have to keep the rpms under 6500rpm (am i wrong?). A couple of the cam companies ive talked to told me that I could do up 6800rpm with a juice roller cam, but that I need more manifold to do that. Ive read about how good the air gap is (though I cant find the damned article if my life depended on it) but is there any benefit to be had with adding a carb spacer? Or how about milling the center divider? Will I hurt low end and gain no noticeable difference in the mid to upper rpm range?

interested to hear what you guys think and any experiences you may have had with this stuff

thanks