Chevrolet: 82 Camaro, gas mileage, timeing

Question
I dont know if you can help but just want to ask.  I have a 82 Camaro 2.8L V6 and the best MPG I have gotten so far is 13, and the worst is 9. I have done a tune up on it put new vacume lines on it but I havent Changed the O2 sencors or the tps but I will here in the next few days thats the only other thing that I can think of. Do you know of anything else of what could be causeing it to get that bad of gas milage even on the highway? What are some sugestions? I am open for anything. I have a 1970 CST that gets 10MPG and it has a 350 bored and stroked 30 over and my rear end is 4:11 locking posie track. I know thats why it gets bad gas mileage but I don't understand the car. That was the whole reason I bought it was economy. Help me please.

Answer
first if you have the 350 30 over you are going to get bad gas milage and with the 4.11 even worse but with the v-6 you should get better than that, try a colder plugs and set the timeing a lil lower and adj. the carb also see if that will help you out