[RET_COP]

It's not that easy just to compare what others are using. You didn't give Intake, Heads, exhaust and air cleaner. What color are the plugs? What type of plug? The gas mileage does not look great at cruise, but it's good for around town. Check your power valve for a possible problem. I'm running a Pro System 780 on a 359w with 76/85 8.5 PV and 11.5" vacuum and my plugs look good and gas mi on cruise is about 18. I tried leaning it out one afternoon and when I reached 72 primary jets the car surged.
I have very good heads, 1 3/4 primaries and a 3"id muffler. My air cleaner lets alot of air through. I could tell you a story about the difference the exhaust alone made on my carb tune. It was significant.