Ok, I'm not a chevy guy but I'm assuming the 700R4 is an overdrive trans. With overdrive I would go around 3.50 for a good performer that will still handle your highways well (gas mileage). The higher you go (3.73) the more she'll launch but you'll start to sacrifice fuel economy on highways. What type of driving you'll be doing is really the most important thing to consider!! I'm running 3.70's in my stang with a C4 trans (no OD), great for cruising around town but horrible on the interstates. But most of my driving is strickly local cruising so I set her up for that.