Got a 1972 Newport with a 400 engine. By this time, they had detuned the engine and lowered the compression ratio to meet solution standards. I want the car a good street driver, but with more power and more fuel efficiency if possible- but still maintaining a good idle. Got any ideas besides raising the compression ratio? Would going to dual exhausts be worthwhile? I would not be opposed to going to headers, either. Would a later transmission that locked up in 3rd gear be worthwhile? I don't think I ever got over 14mpg on this heavy car.