what is the combustion chamber size on stock 91 Z28 350 heads? also what nedds to be done to use early style heads on the 91 motor?

 

64cc heads. on the l98's witch you have

 

Early style (perimeter bolt valve cover) heads will bolt right onto the block, but your late-model intake won't fit because the center 2 intake bolts on each side are canted....you can try to modify it but you'll prolly just have to go buy a new intake manifold. Also you'll need perimeter valve covers.