340 Cranks and other cranks have the 1-2 and 7-8 throw/journal lightened with a hole drilled in or through it. The notch is needed for access for the drill to create this lightning hole.
To the OP, what con rod and what piston do you intend on using? If your changing away from a piston that weighs 880 grams and a likewise porky con rod, a forged 318 crank would be more in-line for when it comes to having the stuff ballanced, (no lightning hole, and more plentiful, more suited to a match in bob-weight requirement with lighter components). If you had no intentions on new rods, pistons and ballance, then disregard the forged 318 idea.
