Action 437 (July 1974) is a 100 page giant, consisting mostly of reprints. The cover image is interesting, you can tell what they were going for, but it doesn’t quite work.
Superman and Green Arrow team-up, to a degree, in the lead story, by Maggin, Swan and Schaffenberger, which re-unites the duo against Effron the Sorceror, who they faced together a couple of years earlier in World’s Finest Comics.
Oliver Queen receives a message from Valhalla, a lost land of vikings, recently introduced in the pages of Superman, asking for help. He heads to see Clark Kent, to pass the message on. Being Oliver Queen, he takes the time out to flirt with Lois Lane first.
Superman and Green Arrow head to the site of Valhalla, but only find Effron, who brags how he has stolen the city, and will destroy it and its inhabitants, unless Superman agrees to become his slave.
Superman agrees, though he will not kill, and “imprisons” Green Arrow in the Fortress of Solitude, after leaving him a secret message. At Effron’s command, Superman seeks out and defeats both the Flash and Green Lantern.
Green Arrow shows up with Valhalla, to Effron’s amazement. It’s not really Valhalla, just Kandor, rebuilt to look like it, but Effron takes the bait and reveals the city’s true location. Superman then takes down Effron, and retrieves the viking city.