Since you aren't running an ARC amp, I really don't see what your concern is. Obviously the transformers in those particular ARC amps couldn't handle the KT-120 tubes. Cary already told you the tubes will work fine in your amp, so what is the problem? The KT-120 tube is like a KT88 on steroids. Everything is better about them. You are really missing out by not using them.
FYI, the newer ARC amps work fine with the KT-120 tubes now.