Karl -
I agree that the "B" block is prone to crack between the # 2 and #3 cylinders (moreso than the "A:" block), but if the main difference to be gained is a balanced crank, then why not add counter-weights to an "A" crank. Admittedly the rods would not be as thick, but I'm not aware that these were a weak point with either of the two blocks. As for the cam, I would think that a "B" grind on an "A" cam might produce similar results. Again, perhaps my ignorance is coming through once more, I'm just interested in learning whatever I can on this subject. Thanks --
Dick