Yet, you have ignored the facts, that Kun is not comparable to DN Luke for 2 reasons:
1) Sources are highly in Luke's favour
2) Kun is a villian, Luke is a hero, obviously, you cannot have a villain winning it all, that goes against the general cliche in book/comic writing, and you're right Luke has defeated villians in HIS time, and merely proving feats that someone double his age, and double his experience, and double the time he had to learn various skills, really puts him above Kun, like i said Kun is relatively only comparable to DE Luke, in which case Kun pwns him
Kun at full potential would defeat any incarnation of Luke ( Speculation ) however its a logical one.