Better stay with something in the high 3's or low 4's if you're planning to use an overdrive 5 speed. A 216 won't have enough torque to run 5th. gear with either of the ratios you've mentioned, and I doubt if it will even pull right in 4th. gear direct drive. With the dual carbs, you'll be lucky to make it run at all unless it's revved up. With the oil clearance adjusted properly, a Babbit-rod engine will handle 2500-3000 RPM without a problem.
Jerry

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