Back in the 1950s, Hollywood producers knew a good book when they read one. That's why the Bible chock-full of drama, not to mention sex and violence inspired a host of big-budget movies. Unfortunately, most of today's moviegoers have viewed such spectacles only on the less-than-wide-screen confines of the tube. But praise be, it looks as if the studios are resurrecting some of their finest epics. Last spring, Paramount attracted crowds with its rerelease of The Ten Commandments (1956), and now MGM/ UA has dusted off the 1959 version of Ben-Hur for a city-by-city caravan tour. The newly restored 70mm print, which runs for 3 hours and 32 minutes, premieres in Los Angeles in mid-September and will be presented just as the original was, complete with overture and intermission. ''There is a real public hunger to see these epic films the way they were meant to be seen,'' says Barry Glasser, senior vice president of publicity at MGM/UA. ''Home video just cannot re- create that experience.'' Famed for its chariot race and sea-battle sequences, Ben-Hur won a record 11 Academy Awards, including Best Picture and Best Actor (Charlton Heston). Its then-record $15.9 million production budget would translate to an astronomical $100 million-plus in today's dollars.