Thanks guys! I'm still not 100%, but I am leaning towards the 440 with a small cam, an optimized ignition curve and a light right foot! It's not going to be a daily driver, and even if I drive it more than I think I will, I don't really think the 440 will get THAT much less mpg than the 318 mag to make a real world difference. I know I'll have to change the brake booster and maybe get a bigger radiator, but I can deal with that. Wish me luck!