Pretty much what Mike said is true. But you could put in a B303 and that will give you a noticeable gain plus it will sound a little choppier. If you are going to put heads on later I would not waste the money right now. You could put on 1.72 roller rockers with the stock cam and that will help as well. I did that for a while when my car was stock efi and it helped it out. Plus the cam and roller rockers are about the same price and the roller rockers require much less labor.

Hope that helps.

P.S. Do you have a blown Cobra like your sig says or something else ?