HOLLYWOOD — Chart-topping rappers Ja Rule and Kurupt have joined the cast of the Screen Gems/Franchise Pictures action film “Half Past Dead” starring Steven Seagal and Morris Chestnut.Writer-director Don Michael Paul helms “Half,” the story of a criminal who masterminds a plan to infiltrate a prison in an attempt to persuade a death row inmate to help him find $200 million in gold from an old heist. Rule, who was most recently seen in “The Fast and the Furious,” is repped by Handprint Entertainment. His latest album, “Pain Is Love,” debuted Thursday at No. 1 on the Billboard 200. Kurupt, who will also be seen in the Kurt Russell starrer “The Plague Season,” is repped by the William Morris Agency.