340 Nodular or 318 steel crankshaft

Nodular iron is a very strong metal, steel is even stronger lb per lb (they are so close metalurgically speaking) . The 318 steel crank has solid throws, the 340 nodular has lightened throws (to compensate for the heavier rods) so it will be lighter in the long run if you plan to use 318 rods. You always want to remove material to balance, much cheaper than adding tungsten. You are going to balance the 318 crank @ about $175 so I would stick with the 340 just as a cost measure if your not going to flog it. Keep balancer of 340, unique.