When you balance an inline 6 cylinder, which is an inherently balanced engine you don’t need a bob weight. I have extensive experience with inline 6 cylinders, and you don’t figure a bob weight, you make sure that every component weighs the same , IE pistons , the big and little end of the rods , wrist pins in my experience the rings and bearings weight the same , and aren’t touched . Balancing is a art anyway, because in a V8 engine you figure a bob weight, and then decide from experience, or other factors as to what amount you overbalance, as in a Pro Stock style motor is over balanced buy up to 150 %
If you want to verify this you can call one of the best balancing shops around, Auto Shop Racing engines, 940 692 1911, they have more experience with inline motors then almost anyone.