Don't bother asking for a specific incarnation of Superman from the Rabidly Pro-Superman crowd. IÆve been in discussion-turn-arguments like this before. You aren't going to get it.
Bullshit raging about an existential non-issue
Confirmed magic users in Dragon Ball have stated that ki and magic are so similar as to be practically the same thing, the only difference being that magic is apparently more versatile in the effects it creates, and that magic supposedly isn't usable by everyone (magic also seems to be slightly weaker offensively than ki, as there are several instances of ki users blasting through things created by much more powerful and experienced magic users in Dragon Ball. However, this could also be attributed to the Main Character Effect, so it's not exactly concrete).
So no. In spite of your attempts to claim otherwise and drag IRL into a discussion where IRL has no place whatsoever, ki would work on Superman in the same way magic would. Goku can't turn Supes into a toad or make him a mortal human on a whim, but he can blast him through a mountain and make him feel it.
If you're going to drag IRL into this to prove that ki and magic aren't related at all, then I'm going to drag IRL into it and prove that:
1.) You can't exceed lightspeed without teleporting or not having a solid physical body made of particles that react to the environment.
2.) There's no atmosphere in space, so Superman using his breath weapons in space or his breath weapons traveling through space is Absolute Bullshit of the highest order, equivalent to leaping over an entire planet of tightly packed Megalodons.
3.) You can't make atoms "more dense".
4.) Seeing things on a super subatomic level is impossible, because the particles in question are smaller than the particles used in the spectrum.
5.) Any amount of absurd and ridiculous bullshit the various writers for Superman have grunted out over the years to make him Yet More Badass, which I could probably list and tear apart all day if so inclined.
Don't start trying to cite IRL definitions of things (like ki) as evidence for or against either Superman or Goku. It's a really, really fucking retarded idea. Stick with canon, nothing else. And since DB canon says magic and ki are essentially identical, and DC (and Marvel, for that matter) can't seem to make up their minds on the subject, I'm going to say a DB/DBZ/DBGT character using DB/DBZ/DBGT ki would work on Superman.