Thanks for all the great info. This is what I came up with and it's purely just for a fun experiment. The crankshaft and rod assemblies are from a 71 40hp. With the rotating assembly on the balance rail, the lower cylinder crank balance lobe always wins out and rotates to BDC. It took over two ounces of weight added to the lower piston to get the assembly to balance out. Since the 71 Piston and rod assemblies are 2.4 Oz heavier than the 60's 3 ring piston assemblies, I replaced the lower piston and rod with the lighter older version while keeping the heavier 71 rod and piston on the top. the rotating assembly balanced out perfectly. With the flywheel on, the the rotating assembly will stay in any position over the 360 rotation. Fired it up and she ran sweet. On the water tonight to see the true results.