Every book I looked in says chevrolet didn't build a 4 bolt 327. But the 327 2 bolt should rev to 6500 R.P.M's if built right . Screw in studs and guide plates are a must . Also pink rod's are also a excellent choice .Good luck That 327 is one of the best engine's ever designed. You should be able to acheive the H.P. that you need.