This is a mod motor guys not a push rod. For a street/strip car with boost and slicks I'd say 4.10's. I'm going down to 4.30's and boost when I put a blower on my car. Need more info on the motor too. If it's built and the valve train too then you can spin it higher. I assume this boost is from a centrify blower then I'd say 6500rpms which leave plenty of room for a bigger gear. If he's using the 3650 tranny his ratios are 3.36/1.99/1.34.1.0/.68. Don't know the ratios for the Aod. -Mark