I assume you mean you have the Edelbrock Performer RPM? The Performer is a stock height, stock replacement dual plane. The Performer RPM is a tall "high-rise" dual plane w/ a cut down divider that makes way more power.

There are a few different M1 manifolds too. The M1 dual plane is just an aluminum version of the factory magnum manifold. The M1 single plane is about as tall as the RPM and available w/ either the 4150 or 4500 flange.

I have no experience w/ how tall of a manifold you can use w/ the air grabber set up, but I bet you can't get away w/ much taller than stock.