My scans? Yes, they're pre-Crisis. DC Presents #27.
Then it's non-canon to the most recent versions of the characters.
What are these "numerous showings" that prove he's more powerful? He was clearly less powerful in Pre-Crisis DC and in DCAU. Have they changed this since Crisis?
The scans you've posted show that he's powerful enough to hurt (though not defeat) Superman, Black Adam, and Prime with a single attack, and that his telepathy can affect even the Spectre. (I haven't read that story, but it looks like he's trying to force Spectre to face some psychological truth rather than just telepathically blast him.)
He's really powerful, and could conceivably beat Superman, but I'd guess no more than one time in ten.
You're basically answering your own question. Supes could never take down Apollo, Adam and Prime like that-- under normal circumstances, he'd be lucky to stalemate any of the three. And like I said, owning Ultraman pretty much proves he can take down Superman in the same way.
Hold on, one time in ten
Manhunter's not that weak, he'd beat Superman more often than not. Even if you just take physical abilities into account, they're in the same league, but Manhunter's other abilities just put him ahead of Superman, plain and simple. Superman has no defense against Manhunter's telepathy, so he'd pretty much be screwed in an all out fight between the two.