As proof the spec market isn’t slowing down for the holidays, Patrick S. Duncan last week sold his drama “Mr. Herrick’s Opus” to Interscope Communications for $ 475,000, with a $ 975,000 bonus when the film goes.Reportedly, Richard Dreyfuss has been in negotiations to star. The company is trying to land “Three Musketeers” helmer Stephen Herek as director; sources expect that the directing role willbe filled “any day now.” The deal was reportedly negotiated by Interscope prexy Robert Cort, Interscope producer Scott Kroopf and indie producer Michael Nolin, who also shepherded “84 Charlie Mopic” and “Live! From Death Row,” which Duncan wrote and helmed. Hollywood Pictures will roll out “Opus” next year, in a pact separate from Interscope’s recently announced output deal with Polygram, which also includes MGM as a potential domestic distribber. The project is about a music teacher whose dream to become a professional musician is not fulfilled as he spends 30 years in the classroom. Only late in life does he understand in what profound ways he has changed his students’ lives. Duncan will have his writing/directing effort “The Pornographer” in competition at Sundance; hisscript “Nick of Time,” about a dad trying to race the clock to save his daughter from kidnappers, is heating up as a John Badham project at Paramount.