#59, Mar-Apr. writer: Conway (with assist from Paul Levitz); designer: Estrada; art: Wood; editor: Conway
#60, May-June. writer: Conway; artists: Keith Giffin and Wally Wood; editor: Conway
#61, July-Aug. writer: Conway; artists: Giffin & Wood; editor: Conway
#62, Sept-Oct. plot: Conway; dialogue: Levitz; pacing: Giffin; art: Wood; editor: Conway
#63, Nov-Dec. writer: Levitz; artists: Giffen & Wood; editor: Joe Orlando
Of course, such a revival (and the concurrent issuance of FREEDOM FIGHTERS, which showcased heroes from the old Quality Comics line that had been bought by DC) was the death-knell of the DC Universe. Too much emphasis and too many crossovers began to take place on Earth-2 and other Earths. Within 10 years, the DCU as we knew it would no longer exist, collapsed upon itself into one Earth with badly botched continuity.
But that hadn't happened yet. In this first issue, #58 (continuing the numbering from the Golden Age), the all-male, all-old team of Earth-2 receive a credible threat that a world-destroying chain reaction will be triggered if disasters in three cities aren't stopped. The JSA splits into three teams to respond.
During the course of the adventure the three teams encounter the recently time-displaced Star-Spangled Kid, a newly-independent Robin (remember, he's the Robin of Earth-2, very much an adult compared to the then college-aged Robin of Earth-1)... And, stopping a volcano rearing over Beijing: a heretofore unseen hero, Power Girl. She demonstrates super strength and the ability to make mighty leaps that are almost flight. In essence, she has the powers of the early Golden Age Superman.

She explains that she chose the name "Power Girl" so people won't confuse her with her cousin, Superman. An editorial note states, "Obviously, on EARTH-TWO, Superman has kept Power Girl's existence a secret LONGER than he did on EARTH-ONE. Honest -- no lie." Well, it might not have been a lie, but there was a little more to it than that as we'd find out.
It is Power Girl who gathered Robin and S-S Kid, calling her team a strike force or Super Squad (a name quickly left behind), but never explaining how she knows about the strike points or why she felt the need to form a strike force. Somehow she's found out that they're up against JSA villain Brainwave. What she doesn't know is that he's using the disasters to reinvigorate fellow villain Degaton.
In the following issue, powered up by the magicks of Green Lantern and Dr. Fate, she redirects a spaceship. "What she does next is a feat which the Supergirl of EARTH-ONE would find almost ridiculously SIMPLE..." We see her sweating and struggling to accomplish her mission, something that would become her trademark. Power Girl was never a quitter (until a 2000 appearance in Birds of Prey, considered out of character but which did give her the nickname "Peege").

Note that she's already changed her costume, getting rid of a probably-irritating rope that ran under her armpit. PG was to vary her costume slightly many, many times and switch to altogether different looks on occasion. I'll try to remember to clue you in when it happens. Usually when I post an illo with an artist noted below it, it's a signal that something different has happened to her costume, though on occasion I use it only to show a particularly new and different art style on PG.

Anyway, the JSA decides to try out the young members of the Super-Squad -- and Peege reminds them that it was they who solved all the problems. PG and SSK were there to stay, but Robin was gone by the next issue. Perhaps the staff knew that someone much more exciting -- the Huntress -- was waiting to debut in a few months.
In issue #60 PG thinks, "I've gotten sick and TIRED of being considered a CHILD -- especially by MEN." Certainly she is now teamed with a bunch of men from a less enlightened era, some of whom do make sexist comments but most of whom give her a chance to prove herself. She wants instant acceptance, though, and it doesn't help that some of the villains she goes up against are sexist as well.
She and the JSA battle a heat villain, Vulcan, in this and the next issue.
In issue #61, Power Girl is level-headed enough to stop attacking the alien explorer Xlk-Jnn, and try to communicate with him. He accidentally created Vulcan and tells her how to reverse the process just before Vulcan kills him.
Note that even now PG doesn't have a civilian name. She's called "Power Girl, " "chick" and "girlie," but the name "Kara" hasn't popped up yet. I'll tell you when it does.
In issue #62, a graying Superman shows up.
Power Girl: "Don't PATRONIZE me, COUSIN! And don't give me any more ORDERS, either! I'm on my OWN now!"
Superman: "So you are... But you can still LISTEN to my ADVICE, can't you?"
PG: "Not any more -- I can't -- and I WON'T!"

Supes: "I haven't STOPPED you, but you can't learn EVERYTHING overnight! Give yourself a chance to GROW..."
This issue the JSA confronts Zanadu, a villain from Mu and Lemuria. NOTE for post-Crisis consideration: this guy is a mystic and calls himself a Lord of Chaos.
Issue #63 pits PG against Solomon Grundy and sees the defeat of Zanadu. At the end, Superman insists that the JSA "elect POWER GIRL to full membership as my REPLACEMENT!"
She replies, "You know, cousin, you're not such a bad sort after all..."