I think that K would beat Ali, and fairly easily. He's a tall guy with a good long jab and he would out jab Ali, like Norton did, and Norton didn't have that kind of jab. Eddie Futch noticed something about Ali- that when he jab, his right hand wasn't there to defend against a jab. So you jab when he jabs- catch his, land yours. When Ali's jab wouldn't work, he would have nothing else to work with. Couldn't fight inside, couldn't/didn't punch to the body.
K would also beat Holyfield pretty easily because Evander was never very good at all at avoiding jabs. (See the Lewis fights, Moorer 1, etc...). If K fought him, as he seems to fight most people, by jabbing, then stepping back or around to maintain his distance, it is an easy fight for him. Keep him on the end of the jab and that straight right hand.
I think the early Foreman beats him because of, again, his jab which was very underrated in the first potion of his career. He could also take a punch, get up and win a war, as he did in the Lyle fight, and I don't have faith in K's ability to do that.
Holmes is an interesting proposition, because he, like Ali, relied on his jab. Much harder jab, though, and Larry could fight a bit inside when forced. Good right hand, too, but, honestly, and though I hate to say it, I think K could beat him, if he jabbed, maintained distance, and didn't get clipped with a right from Holmes.