I took my car down the track for the first time and did ok for being a driver and not anything special as far as engine/trans/rear end goes. It's a 1970 Monte Carlo with a 327 and TH350. Someone asked what gear I had in the rear end. I have no clue, but it gets decent mileage, doesn't wind at highway speed, and is slow off the line. I figured I would try to figure it out. It's not a posi because one tire turns one way and the other turns the other way. What I did was put it on blocks, blocked one wheel, counted the tire spins to the driveshaft spins. I rotated the tire 10 times and the shaft rotated about 12.75 times. Then took the formula I found online (shaft spins times 2, divide by 10) to get 2.55. The closest ratio to that is 2.56 for a GM. Did this formula and numbers look correct?

If it were a 4.10 ratio the tire would turn 10 times and the shaft 20.5 times according to the formula. If both a 2.56 and 4.10 were running the same RPM's, which tire would turn faster? I'm assuming the tire that turns faster would be faster off the line and thus be the 4.10, correct?

Would a 2.56 or 4.10 get better:
Gas mileage-2.56
launch on the line-4.10
lower RPM's going 65mph-2.56

They may be stupid questions to some, but my mind was wondering and thought I'd ask here.