I ported my 302 casting heads,and left the small valves in.My 318 screams all the way to 6500.I didnt go wild with the port work,just opened the bowls to valve seat size,and a good blending so the turns are nice and smooth.I also gasket matched the intake side to 340/360 size,and matched the weiand stealth intake too.on the exhaust side,i gasket matched also,and did more porting than the intake side.Ive done 2 sets of these heads now,and both perform remarkably well with such small valves.