the Z32 was designed they were pretty rare. Going with a taller rear end, or wider gear ratios have their disadvantages. My point is that the design was pretty state of the art back then regardless of the 55 mph speed limit in the us.
I remember when overdrive was kind of a big deal. I had a Camaro with powerglide transmission when I turned 16. That's a two speed automatic without a lockup torque converter.