I found this in my ZR-1 file. Marc Haibeck is apparently the author, and should shine some light on speed vs. rpm vs. differential gear -
as it pertains to standard tire/wheel size of the ZR-1 (only).
However....As others have said, if shift points are important, then a shift light is the way to go. And, I would say that is true whether you drag race or not; just good to dial in the best shift point on the light, and end the guess work.
Just sayin...
P.