Chevy Girl-
You can definatly increase your top end by going with a set of 3:55's, Taller tires (30") and a T-5 tranny from a Camero/Firebird. I have a 292 /tri-power and it has all of the above, and I cruise at 65MPH @2,000 RPM's. That worked out to 18 MPG for 3,000lb car. At 75 MPH, it was only reading 2,200 RPM's but the milage dropped to 13MPG. I guess the secondaries started to come in.
Good Luck!
RapRap
1940 Chevy Coupe
