You'll need file fit rings because KB require special ring end gap measurements...generally accepted ring end gap is 0.004" per 1" of bore (e.g., 4" bore would equal 0.016" end gap), KB on the other hand requires minimum of .0065" per 1" of bore, in that case a 4" bore would require a .0265" ring end gap. And that's minimum measurements for N/A engines. Power adders are more due to the increased heat soak in the top of the engine.
The brand isn't as important...if KB has a recommendation, use them, but I believe my brother bought a set of Sealed Power file fit moly rings for his 340 build with KBs