You've got a classic case of over-carburetion. You need to find carbs with smaller venturis, to avoid killing the venturi vacuum as the throttles are opened. The Carter carbs intended for the 216 engine will be better suited for a basically stock 235. Two Rochester carbs intended for a 235 might work if the engine is highly modified, with lots of cylinder head work and a radical cam, or for a somewhat warmed-over 261, but they're WAAAAAY too much carburetor for a stock 235.
Jerry

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