What gears does my bud have?

A friend of a friend came down from Austin and he has this nice Z28 Camaro with a 'built' rear. Car is set up for bracket racing but this just what I hear. He had one before but this one came with all the mods and he is not sure what it has on it (He hasn't had it very long). Long story short he says at 80 MPH he turns 2250 RPMS and I told him mine with 3.42s (C5) turns 1750. Assuming he has a T56 what is he running, my caculations came out to 4.30s but that can't be right, can it?

If you can tell me the tire size and RPM or speed, I can tell you the rear end assuming a stock transmission.

I KNOW the gears for a 2002 SS M6. If it is any other year, what is the trans ratio in the gear he is in when turning the RPM or speed?

If you want a spreadsheet on it, I can send if I have your email address.

I was @ 80 the other night and was just barely above 1500.