My truck has a worn out 250 with a Holley/Weber 5200 carb, 3 speed saginaw with no overdrive, and 4:11 butt gears. The biggest problem I have running at freeway speeds is gas mileage. I'm turning so many rpm that the engine is just SUCKING gas. When I drove around local and back and forth to work I hardly ever go over 55 or 60. I get about 14-16 mpg. Running at freeway speeds I get 10-11 mpg. That's one more consideration.
Boo
