Does anyone have experience with this offenhauser 2x4 intake ?

Indy makes an Intake manifold called The Modman. It has replaceable tops. One variation is the dual carburetor top. It LOOKS fantastic but simply is not a good manifold for a street engine. Its best variation is a roots blower top: This outdated link is just for visual reference only. FOR SALE - Dual Quad Indy Intake with Edelbrock 750's