Which one is bigger?

1969 340. I have pulleys that line up fine, but my crank is smaller than my water pump. The crank measures 5 7/8 measuring outside diameter. The groove for p/s on the crank measures 6 5/8. The water pump measures 6 3/4. I also have a single groove crank pulley that is the same 5 7/8. Just wondering if the 340 had different pulley setup than 318.