Neutral balance to a 360 crank?

All 273/318/340 that were internally balanced have different bob weights. 273/318 are pretty close. The 340 has a way heavier piston and so the crank needed to be lighter. So different bob weight. You can tell a 340 forged crank by it having the front and rear journals drilled with a 1 inch hole.You can’t randomly switch just the cranks from a 340 to the others. They want to balance the rotating assambly cause a few grams here and there can add up pretty quickly. Hope this helps. Cast cranks are cheaper to make. They started them in 68 on the 318. Then 71 on the 360s and 383 2 barrel motors. Then 72 400 and then the 73 440. It all cdd as me down to cost per item. Kim