I did the 360 2bbl swap on my 318(out of a 77 B200 van, Holley 2 bbl), and I love it!!! So much smoother to drive, throttle response is right now, and gas mileage didn't change at all (not that I care about gas mileage)....... Of course, maybe the BBD I had on the 318 was a piece of crap......