Looking for better fuel milage

I get 18 mpg hwy in my Newport w/ 383. A light Dart should do much better. I added the Holley Pro-jection 2D in 1996 but no noticeable improvement over the 2 BBL carb. I agree that your main problem is cam, intake, converter all for racing.

A fairly inexpensive upgrade is to add an O2 sensor to the exhaust. Without it, hard to say what your carb is doing. Holley has a little 3 LED monitor box. List for $120, but I got much cheaper on ebay. Before I found that I was using a 1 LED box from a natural gas system I got on ebay w/ O2 sensor for ~$10. w/ dual exhaust double everything or just monitor one pipe. That will set you up for later EFI systems like Pro-jection, MegaSquirt, FAST, etc.