so your getting new pistons a 3.3/16 bore is huge for a grey engine make sure youre rods are resized and balanced with "new" gudgeons and new rod bolts try lightening youre flywheel to reduce youre rotating mass.. when balancing youre crank have the flywheel and balancer done aswell together as for your cam dont get double valve springs if they are not needed grinding youre head for increased compression will help good luck andy