Rucker overhead valve conversion

[fortyfords]

What would be a good rear end ratio to run over the high cost of a Mitchell overdrive unit. This Rucker runs two Stromberg carbs and headers. Don't know anything else about the engine but it sounds healthy. It's in a stock 30 Model A coupe. For instance, would 3:00's be too tall or would a lower 3:50 ratio be better? I hope this is enough information and if anyone has experience with Rucker setups, I would appreciate hearing from you. Thanks for any help