In my oppinion, moveset is way more important than IVs.
But here, the problem is different: Machamp has no good moveset at all. Karate Chop ist really weak, Stone Edge seems to be ok, but misses stab.
I have got a Machamp with Karate Chop, its a funny animation, but it is simply to weak, there is only little damage done to snorlax, his want-to-be-victem. I don't use this guy.
I think, he is not really worth powering up. I suggest, you go out and look for a gym to test him for yourself, if not convinced.