Bates and Saaf give the Justice League a small role in Supergirl 8 (Nov. 73).
Linda Danvers has a new boyfriend in this issue, Mitch. The two of them are rehearsing a play about Medusa, in which Linda plays the title role, and Mitch plays Perseus. The show is being done because one of the profs at Vandyre has discovered what may be the location of Medusa's tomb. The professor gets attacked, and Linda goes into action as Supergirl to save her. She does so, but winds up with a headful of snake hair as a result.
The thieves wind up turning to stone when they see her. This makes the news, and Justice League members Batman, Green Lantern and Hawkman come to check on Supergirl. They want to bring her into custody until a cure can be found for her condition. She insists she can find a cure on her own, and in the ensuing battle the three Leaguers wind up turned to stone as well.
At that point the snakes begin talking to Supergirl, and she learns that she has become a victim of the vengeful ghost of Medusa.
Supergirl flies off to find Medusa's tomb, but as this is going on Mitch winds up possessed by the ghost of Perseus, and goes after her. That completely does not explain why he is suddenly able to fly.
Once Perseus determines that Supergirl is an innocent victim of Medusa they team up to find her tomb. She proves not nearly as much of a threat as she might have been, as a cave in buries her and ends the spell. Supergirl's snake hair disappears, and the people turned to stone recover.