Most moviegoers may not pay much attention to the Roman Catholic Church's ratings system, but the church still wields considerable power over the movie business in Italy. That's one of the lessons learned by the Hollywood-based Cinema Arts Corp., which is footing the $12 million bill for a film about the brief reign of Pope John Paul I, who died 33 days after he became the pontiff in 1978.

Five books have already been published on the subject, all of them advancing conspiracy theories. Appropriately enough, the forthcoming film is titled "The Conspiracy" -- though its producers say they're relying on original research rather than previous investigations. It stars Robert Mitchum, Christopher Walken and Paul Scofield (as John Paul I) and was originally to be filmed in Rome. CAC President Richard Martin made four trips to that city to lay the groundwork, but in the end, to nobody's surprise, he decided the location posed too many problems.

One was that the film might anger some underworld figures named in the script. A bigger worry was the Vatican itself. Even the Italian government is "very concerned with what the Vatican thinks," says executive producer William Bairn, who says his script isn't really anti-Vatican, although it does deal with factions within the church. Shooting is now scheduled for this fall, mostly in Yugoslavia -- Dubrovnik doubles for Rome, and the city of Split is said to look just like Milan . . .

"Has James Bond finally met his match?" That's the question asked in the ads for "A View to a Kill" -- ads that also picture Roger Moore's Bond standing back-to-back with his latest and apparently most formidable foe, the lithe, muscular and menacing Grace Jones. Maybe 007 has met his match and maybe not (far be it from us to give away the ending of the 14th Bond movie), but it can be said with certainty that Jones has -- in the lithe, muscular model-dancer-weightlifter Stephanie Suthers. The Los Angeles Times discovered that Suthers modeled for the advertisement because Jones was unavailable. For the record, Moore had a stand-in, too -- but then, his body is hardly as distinctive as Jones' . . .

"Two Jakes" stubbornly refuses to die. In fact, it's absolutely thriving on the Hollywood rumor vines. No sooner had Paramount pulled the plug on the "Chinatown" sequel -- because of disputes that arose when director-writer Robert Towne decided he didn't want coproducer Robert Evans playing the chief heavy -- then word began spreading that the project might be started up with a new studio (MGM/UA or 20th Century-Fox) and/or a new costar (Roy Scheider or John Huston) and/or a new director (Huston).

By now the rumors about Huston's involvement have lost steam, and Fox says it's no longer negotiating for the rights, but MGM/UA still figures prominently in most of the scenarios. Paramount, which reportedly has sunk about $4 million into the film so far, is conducting any acquisition talks very quietly, and Towne, for one, said, "For the sake of my sanity . . . I don't want to know until it's resolved" . . .

"Two Jakes" star Jack Nicholson, meanwhile, will soon be seen in "Prizzi's Honor," an odd comedy directed by Huston in which rival Mafia hitpersons -- Nicholson and Kathleen Turner -- fall in love and marry. It's one of this summer's few movies aimed at grown-ups, but initial rumblings from the Fox lot hint that few moviegoers of any age will be enthusiastic -- even if it does seem to be a typical film for Turner, in that the sex scenes are causing quite a buzz . . .

He's been everything from a rock 'n' roller to a preacher, but so far Little Richard has never been a movie star. Now the flamboyant singer gets his chance -- he's just joined Nick Nolte, Bette Midler and Richard Dreyfuss in the cast of Paul Mazursky's "Down and Out in Beverly Hills," a Touchstone film that started shooting last week. Little Richard plays a role he ought to be familiar with -- a record producer named Orvis Goodnight . . .

When "The Trail of the Pink Panther" was released in 1982, many critics found it insulting to the memory of Peter Sellers, composed as it was of outtakes from the five Pink Panther movies Sellers made. A British judge has agreed -- on Memorial Day he awarded Lynne Frederick, Sellers' widow, a $1 million settlement in a lawsuit she brought against United Artists and director-producer Blake Edwards. The judge refused, however, to prohibit future screenings of the film.