“Viva Forever,” the long-gestating tuner springing from ’90s girl group the Spice Girls and produced by “Mamma Mia” creator Judy Craymer, is eyeing a December berth at the West End’s Piccadilly Theater.A spokesman for the show refused to comment on the rumor. The Piccadilly is currently home to the original London run of “Ghost,” which opened in July 2011. The show has not posted a closing notice. With sales of 65 million records, the Spice Girls are the bestselling girl group of all time and the most successful British band since the Beatles. Not a bio-musical,”Viva Forever” is scripted by Jennifer Saunders (“Absolutely Fabulous”), who had a cameo role in “Spice World,” 1997′s critically mauled but profitable movie tuner about the run-up to a Spice Girls concert. The tuner’s creative team comprises helmer Paul Garrington — replacing Marianne Elliott (“War Horse,” who ankled the project last year) — designer Peter McKintosh (“The 39 Steps”), choreographer Lynne Page (“La Cage aux Folles”) and orchestrator Martin Koch (“Billy Elliot”).