If Larry Kirwan hadn’t been a rock ‘n’ roller, he’d probably be a great Irish American author. Wait a minute, he’s one of those too, with several plays and two outstanding books — Liverpool Fantasy, the story of what the Beatles would have been like if they never made it, and the gripping autobiography Green Suede Shoes. But it’s his writing with his band Black 47 that really sets Kirwan apart. He’s written as eloquently about the American landscape over the last two decades as such better known songwriters as Bruce Springsteen. Bittersweet 16 is a typically quirky Black 47 retrospective that touches the important bases without ever seeming like a greatest hits album, including enough alternate takes and rarities to attract the most hardcore fan.