My dad and I recently acquired an old 401 Buick with plans to put it into a street rod. So we found a nifty lookin' dual quad manifold from Offenhauser, but we'd like to block one of the intakes off and run the nailhead on just one carb. We've heard about guys doin this before, but we're not sure which intake to block off, front or back. Again, it's an Offenhauser dual quad manifold. Thanks for any educated info you have.