It’s hard to imagine, but there was actually a time when radio was interesting, unpredictable, even inspiring. And there may be no better example than the early days of Boston’s WBCN - from, say, 1968 to 1974 - when the DJs not only played what they wanted but also had the freedom to opine about the important political and social happenings of the time. As the Velvet Underground’s Lou Reed sang in 1970, “Despite all the computations, you could just dance to a rock ‘n‘ roll station, and it was alright.’’ Well, filmmaker Bill Lichtenstein, who worked at the station back in the day, is making a documentary about WBCN called “The American Revolution,’’ and he’s trying to raise $104,000 for the project via www.KickstartWBCN.com.