FYI..Pulled the Mercruiser down to find the crank has been balanced at Chevrolet or who ever put these motors together for Mercruiser.The rods look to be stronger and have been balanced.The pistons were cast but I looked in the piston book and it showed that some came with forged pistons.The cam has somewhat higher lift and the GM# is 3891580...Wish I had some way of finding the specs ??? When I put it back together I will put a degree wheel on it and let you know. Going back with 307 flat tops .020 over and larger valves in a 184 head....should run plenty good for my 50 Chevy..SCRAP
