I would use nothing more aggresive than a .425 lift and 225 duration. Good luck trying to get decent mileage out of a Super Six 2bbl setup. Never got better than 14MPG with mine. Anything higher than 9.0:1 is asking for pings on 87 octane fuel. Maybe not in the first few thousand miles but wait till you get a bit of carbon buildup. Maybe I've been lucky, but I've never seen a stock slant 6 lose a timing chain....let us know what you find!