It's hard to beat a 9" Ford. There's a billion of them out there, and they're plenty strong. The ratio depends on your tires, your motor and your vision for the car. Do you want a cruiser, or one that accelerates like a turpentined cat? You want to zip along at 70 mph and 1800 RPM or do you want to look like the guy in the Alpine ad? If you've got really tall tires, you can go with lower gears. With "normal" size street tires, you can go with higher gears. A bucket is so light it will accelerate without super deep gears. If you've got a radical engine, you may want lower gears to make up for a fast idle and less low end torque. If I was building a bucket, I'd use a Ford 9" with 3:73 gears, but that's just me.