Smallblock Pistons: 1 question.....KB's -or- Sealed Power(SpeedPro hypers)???

Again, the brand does not dictate the strength... the type of piston does.
Speed Pro, KB, Mahle, Diamond, Wiseco, Manley... all make both forged and hypereutectic pistons. In every brand, the forged style are the strongest.
You shouldn't choose pistons by the brand name!