There's a reason the GM engineers only put one 1-barrel carburetor on those engines for over 30 years- - - - -they work that way! A 4-barrel or a fancy multi-carb setup is only eye candy. It does nothing to improve performance, and usually makes the engine super-sensitive to slight changes in throttle position. If you want a rig that stumbles stalls, farts, snorts, and backfires a lot, go ahead and put too much carburetion on it. A race-modified 261 engine can benefit from extra carbs, or a 4-barrel, but increased intake flow capacity on an otherwise stock engine is only a small part of the total performance package. If you've just got to have that dual-carb setup for looks, find a manifold for an old 216 with the close stud spacing, and put the smallest-venturi 1-barrel Carter carbs you can find on it. Then you'll only be slightly over-carbureted, and if you do a good job of synchronizing and tuning those carbs, the performance won't suffer as much as if you use two of the big Rochesters designed for a 235. I think there's a very low-volume Carter 4-barrel available, but it's still got more than twice the CFM capacity a 235 needs.
Jerry
