Art Basel buzzed yesterday with word that Jeff Koons will launch a show in May with the David Zwirner gallery in Chelsea and not his usual Gagosian Gallery. The news came as Larry Gagosian shows Koons works at his Basel booth, where collector Eli Broad bought a sculpture of Buster Keaton for a reported $5 million-plus. But a source says the jump to Zwirner doesn’t necessarily mean Koons is completely changing allegiances. “Jeff was obviously ready for a change,” said an insider. “But changing ‘representation’ is the wrong word. Larry’s presenting Koons’ work in his booth and he has sold a lot of material. But it’s thrilling for Zwirner for [Koons] to shift” to another gallery for a show. A Koons sculpture was recently cited in a suit between Ron Perelman and Gagosian, in which the Revlon mogul accused Gagosian of fraudulently undervaluing the work to the gallery’s benefit. Gagosian also sued Perelman, claiming he agreed to buy $22 million in art and refused to pay.