cleveland mains are SMALLER than the windsor mains. one of the problems with the cleveland oiling system is that in stock form it oils the cam bearings first, the mains next, and the rods last, which is why the good cleveland builders install the oil restrictor kits i listed in their clevelands. and you can always cross drill the mains and rods to improve oiling further. the other issue that the cleveland has is cylinder wall cracking due to the shorter rod and the resulting higher thrust loading. personally i do prefer the 351 motorsport block that has 351c mains, 351w oiling, allows for 351c heads, and the taller 351w deck height.