The regular oval port, big block performer intake runners match the small oval port heads (plenty of material to port to the larger oval port head). My assumption would be that the RPM version would be the same, but You might want to check with Edelbrock. It would hurt flow if the intake port was larger than the head, Not as bad the other way around.

 

I did this with my 86 suburban that had a 454 with peanut port heads. Use the RPM manifold and stick on some headers and it will wake that thing right up! The heads are restrictive compared to older heads and aftermarket heads but you can make plenty of torque with these things.