I GOT 2 MERCRUISERS 454 7.4L AND 1 HAD A PROBLEM IN IT AND I REMOVE IT FROM THE BOAT THIS ENGINE WAS OPPOSITE ROTATION AND THE ONE I GOT TO REPLACE IT WAS STANDARD ROTATION NOW I CHANGE THE CAMSHAFT AND THE TIMMING GEARS AND THE BACK OIL SEAL DO I HAVE TO CHANGE PISTONS?? THANKS:smt100
