Wiseco PTS Series, 4032 aluminum, flat top pistons in Buick 455 engines will generally provide compression ratios in the 11.5 to 12.8:1 range which makes them a good option for engines with aluminum heads and larger than stock camshafts. Valve reliefs are configured to work with most types of standard and aluminum cylinder heads and will normally fit camshafts to well over .600 valve lift.