Matching the right gear ratio to the tires

I'm an owner of a 71 Nova with a 454 engine that I have just finished putting over 8 grand into. I've had it dynoed recently with an engine dyno rather than a rear wheel dyno and it came out with numbers I liked. I have one question about the gear ratio. If I'm going to put on mickey thompson sportsman tires (31X18.50) on a 35 spline axel. I was told I need a gear ratio in the low 5's. I myself was thinking maybe 5.29, but I want a few more opinions before I do this.

I just checked my book and couldn't find the math problem to figure this out. However I know the guys who know the answer right off will ask..what transmission your running, with what gear ratios in it, what is the redline and peak horsepower of the engine, and what are you doing with the car. (totally strip or street/strip?)

The horsepower of the car right now is 570. This is the transmission I will be going with from summit racing part #TCI-212500. The first gear ratio is 2.48, with a 3,000 rpm torque converter that will be installed. Mainly the car will be a weekend warrior with the occasional trip down to bakersfield track. Track use maybe 3 or 4 times out of the year.

scratch that 31x18.50 not 29