It's fun that they get a meetup that doesn't immediately turn into punching, or worse, Superboy-Prime.

From 1991, Superboy #16, "Metropolis: City of Tomorrow...Today!" Written by John Moore, pencils by Curt Swan, inks by Kim DeMulder. Cover by Kevin Maguire and Ty Templeton.

We've seen a couple of these, tie-ins with the syndicated Superboy TV show; but this would've pushed the budget a bit too far. It's the conclusion of a time-travelling two-parter, as young Clark has an adventure in the Metropolis of the year 2240 with some "genetically altered J.D.'s" with an albino tiger caretaker, and the time-traveler Dancer, who brought him to destroy a malfunctioning time beacon. But, instead of 1991, he's returned to 2001! It takes Clark a moment to put that together, even after he sees himself fly into a white time void and disappear.

Clark figures, if he saw his future self, that must mean he gets back to 1991, right? Unless the whole timeline goes blooey or something. Still, he sees his old friend T.J. White on a storefront TV--man, there's a plot device that's gone away--and goes to him for help. T.J. believes him, since Clark was ten years younger than he should be, and takes him to the Daily Planet, where he would work in the future, but to see someone else. Clark takes off his glasses, and is introduced as his own cousin, "Clark Shuster," to Lois Lane and Jimmy Olsen! T.J. knows Lois is going to be the one to figure things out, even if she is snowed by his lies about Clark's time-travel expertise. The four head to S.T.A.R. Labs, to see temporal physics expert Jessica Gary, and get there in time for another time rift to open, this time like a sinkhole. Clark thinks it's a path into the timestream, and Lois asks why he's the expert: Clark is about to come clean, although I don't know how much he was going to tell her, but is interrupted by Jimmy Olsen activating his signal watch! Clark can hear it, and is unused to the signal, so he's almost in pain. Jimmy thinks the watch must be "on the fritz," otherwise how could Clark hear it? You're...you're so close, Jimmy!

Dr. Gary and Clark climb down the time sinkhole, which changes Clark's clothes to Superboy's, then Dr. Gary slips, falls, and disappears. Superboy is lost in a featureless temporal soup, but comes through, to find Superman, on a sphinx! Superboy recognizes it as Dancer's headquarters, and they find an albino tiger cub and Dr. Gary inside. The doctor was acting weird, and her voice seems to have a reverb effect, but she deactivates the sphinx's time machine, then gets zapped out of existence! Only to return a moment later, as Dancer: she had set this up in the future, so she would be able to make things right. Superboy and Superman return to S.T.A.R. Labs, where Lois has questions about what happened to Dr. Gary and Clark Shuster, which Superman doesn't really want to get into but kinda seems like she'll wring it out of him. Superboy then disappears, returning to 1991 and Lana, who doesn't seem particularly interested in hearing about Clark's trip. 

 Perhaps serendipitous, but there's an ad for Armageddon 2001 in there, too! I had to take a look: this would have been just a couple months after Curt Swan got to do a few pages for Superman #50. He had been the Superman artist for so long, but DC seemed to think he was old hat: I wonder if his work on this series was an olive branch...or a consolation prize.