My car is a real one with this rearend. Does anyone else have the rear?

This question has been asked and answered before. The answer is yes. Any ration could be ordered. I am surprised there are not more with this gear ratio. 150+ can be achieved with this gear.

Z/28 was more about acceleration than top speed. (Remember, it was theoretically a road racer) The numerically lower the rear, the harder it is to get it going, but top speed increases. Today's cars often have overdrive to give you good acceleration, as well as good highway performance (read, gas mileage) Sixties Muscle did not really care about gas mileage. When mileage became an issue, the muscle car era died a painful death.