Okay so I don't know if this would be better suited in the Before Black section but I think I will try it here: After some thought I have decided it would be fun to see just what kind of fuel economy I can get out of a carb'ed normally aspirated 231. I have decided on going with a COMP High Energy cam (252 advertised/.425 lift), an Edlebrock Performer intake and some custom grinding on the stock (1979) heads. My main question is about pistons, the engine is currently all stock and has 127,xxx miles on it so I'm sure it would be for the best to clean up the bores and probably go ahead and do a .030 overbore. Obviously that means new pistons so here is where my problem comes in: I know higher compression equals both more power and better engine efficiency. The only pistons Summit racing has for a 231 are dished but they have some flattop Olds 307 pistons, I have heard they interchange but I'm not sure. Also what carburetor would you recommend, I'm leaning toward a 450 vacuum secondary Holley but is there a better choice? Remember I'm building this for optimum fuel efficiency so power isn't a huge priority but I do want good throttle response. My goal is 25MPG highway, and somewhere around the 180 horsepower mark. I assume that's a fairly realistic goal so do you think my plan will hit that? I will be running a 200-4R transmission and the stock 3.08 rear gears. Any tips and advice are appreciated. I do also want to try to keep this build under $2500 and its got to run on 87 cheap gas. Thanks and God Bless