[19673ontree]

They are not talking about the heads when they say 283 327 they are talking about the block the 283 327 blocks have a breather in the back of the block and no holes in the valve covers the oil is poured in the engine thru the intake in the front , the heads fit from 1955 to whenever they stopped mmaking smmmall block chevy engines but as mentioned above the vortec heads are different ,,