World Products 030630M-2 - Cylinder Head Cast Iron Chevy Big Block MERLIN 345cc Rectangle Port Marine AssembledWorld Products Cylinder Head Cast Iron Chevy Big Block MERLIN 310cc and 345cc 26Degree 2. 300 x 1. 880 MARINE VERSION comes with Inconel Exhaust valves Worlds MERLIN series has earned a reputation as the performance industry standard for Big Block Chevy power. The cast iron MERLINS are available in both oval and rectangular port designs, with intake ports offered in 310 & 345cc configurations. Choose the port size that will provide the optimum balance