How much money do you want to spend? The 4.10 gears coupled with that 3.06 first gear should launch your car like a rocket. Are you certain they are 4.10's? To get more mid-range torque you should really upgrade your cam and heads. Vortecs are the most bang for the buck but you will have to get a compatible intake manifold. As long as you stay with a cam with no more than .470 lift, you should be okay. What are you running for a carburetor? What kind of vehicle? What size rear tires? Can you provide more information?