I have a 70 Chevelle with a green vinyl top thats in good condition but just a little faded. What can I do to clean it or make it look better than it does now. I have heard of using COMET but I dont if it will damage it or not. What good product should I use??

Try a mechanic's type handcleaner with pumice in it, apply some to the top and use a good brush to work it well then wash with water, follow up with a good vinyl top preservative. Some floor waxes work well for this also- that's all I used years ago.