Ah, my brain is slowly getting back into gear now:
Yes, the Ks still had four bolts, but they are a much larger block than the earlier type. Seem to recall there being a difference in the shape too - maybe a curve on the top and bottom edges?
I can ramble all night about stuff I half remember...be worth checking the part number/diagram of reed block itself, and the gasket. If I'm right, the K reeds (and block) are way bigger.