5.9L Magnum build with questions

So that would stand to reason that you could put a set of kb107s into a 5.9 mag with no need to rebalance.

5.9 mag - 469g piston 135g pin 604g total
kb107 - 524g piston 132g pin 656 total

52g difference
That’s correct. Apparently the factory rotating assembly was way off balance and not spot on like you would assume it would be. Like I said though, I still went ahead and had my rotating assembly balanced. I just didn’t want to take a chance on what is turning out to be an all out engine build instead of the quick refresh I was originally thinking.