360 Intake Manifold

Hey all I have a 360 with keith black pistons and a 292/508 cam. I recently bought a holley 750 DP carb to use and it is too big for my current single plane intake (current is 4.5 inches across, holley is 5.5 inches across, so I am going to replace my intake manifold since others have suggested replacing it anyways. Ideally I want something around $200-300 and something that gives me good low end as I am trying to build the engine to have quick acceleration. Someone in another thread suggested a RPM Air Gap, does anyone have suggestions on which intake I should get? Thanks.