Sylvester Stallone, onscreen this summer in “Cop Land,” is close to inking a deal that would reunite him with director Renny Harlin on New Line Cinema’s “Frequency,” sources said Thursday.The pair climbed mountains together for “Cliffhanger” in 1993, a pic that grossed more than $200 million worldwide. It was unclear whether New Line will pony up Stallone’s current action quote of $20 million. Sources said his back-end participation could put him well over that figure if the pic is a hit. Both the studio and Stallone reps made it clear that the deal was not yet finished. “Frequency,” penned by New Line’s prexy of music Toby Emmerich, is described as a big-budget, character-driven actioner. Stallone would play a New York City fireman in 1969 who is able to communicate over a ham radio with his son, a homicide cop in Gotham in 1997. When the son realizes he’s talking to his father, he tries to warn him of his impending death in an urban blaze. Stallone has recently been vacillating between hardcore actioners like Universal’s recent domestic disappointment “Daylight” and more character-driven pieces like Miramax Films’ “Cop Land.” “It’s a great transition for him because it’s sort of a hybrid of what he wants to do and what he’s done,” said one source close to the deal. New Line wants to get the picture into pre-production over the next eight weeks and start lensing toward the end of the summer. New Line president of production Michael De Luca and exec VP of production Richard Saperstein are handling the project. No producer is yet attached to the pic, but Harlin and Stallone are both expected to take a role in producing. Emmerich will exec produce. Harlin last directed and produced “The Long Kiss Goodnight” for New Line. The $65 million-budgeted pic garnered only $33 million in domestic box office and another $48 million overseas. Harlin was said to be miffed over New Line’s marketing of the pic. His production deal for the Forge with wife Geena Davis is with New Line. Stallone is being repped in the deal by Fred Specktor of CAA and attorney Jake Bloom. Harlin is handled by Jim Wiatt of ICM. Emmerich’s exec producing deal was brokered by his attorney Jeff Blye.