A Sealed Power, Silvolite, Ohio, Badger, Zollner, Hy-Duty, Nylen or Clevite piston would be a stock replacement.
KB pistons are supposed to be high performance and even if they don't cost too much, it is ASSUMED that the purchaser knows they will make rebalancing necessary. It's the same for the ring gap requirements.
I salute KB for making an affordable piston for a 340 that actually weighs like a smallblock piston and not a bigblock piston. But if your point was that a 340 needs to be rebalanced when using that piston you are absolutely right. No way is a 200+ gram difference going to go unnoticed, and probably right from idle and on up.

R.