Well, I have to ask.... Why do you want to go to fewer cubes???? Mini mouse motors were ok in there day, and then only in light weight cars.... A good street motor needs to make torque at low rpm, not horsepower at 8500. The novelty of having a mini motor wears off quickly when the valve train and other internals continually fail because of the extremely high revs you have to twist the engine to make any power.
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Why not go the other way, build your 350 into a 383??? Get the correct cam and head combination to build low rpm torque....