The 2:80 (this means the driveshaft turns 2.8 times to make the rear wheels turn once) gears will give you a high top speed and good fuel mileage, But a 3:55 would be a good choice for better acceleration. The rear end gears work similar to bicycle gears. On a 10 speed or mountian bike, the lowest gear will be easy to pedal and you can accelerate fast, but you will have a low top speed beacause your speed will be limited to how fast you can move your legs. This would be similar to a 4:10 gearset where acceleration would be fast, but top speed would depend on how high you want to spin your motor. In the highest gear on a bike, you have trouble starting because it is so hard to pedal, but once you get moving it gets a little easier. You can go much faster moving your legs at the same speed as before. Your acceleration would be slow, but you would have a high top speed. This would be similar to a 2:80 gear. I would recommend 3:55 for your application for the best combo of acceleration and reasonable highway rpms.
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67 Fastback - Arctic White Pearl paint
351W 415 hp, Trick Flow Alum. Heads, C-4 Trans, 3.55 gears, Front Disc Brakes, 1-1/8" Fr. 3/4" rear sway bars.
