ROME — Helmer Lasse Hallstrom’s “Casanova,” shot in Venice, will world preem at the 62nd Venice Film Festival.Fest director Marco Muller, in his second year on the Lido, has pacted with pic’s Italo distribs, Buena Vista Intl. and Touchstone Pictures. “We have been courting the producers of this film since last year,” Muller said Friday. Heath Ledger stars as history’s most notorious seducer, who finds himself spurned by the feisty Francesca (Sienna Miller) in this romantic comedy. For the event, Hallstrom will be on the Lido with producers Mark Gordon, Betsy Beers and Leslie Holleran and thesps Ledger, Miller, Jeremy Irons (who plays Bishop Pucci) and Lena Olin (Francesca’s mother). The fest runs Aug. 31-Sept. 10.