As Steve Lawrence is to Sinatra, I always figured Lou Rawls is to Billy Eckstine. Like Lawrence, Rawls was blessed with impressive pipes, impeccable timing and respectable taste in material. His is, overall, a dynamic talent, yet it’s neither quite as startlingly original as Eckstine’s (or Sinatra’s) nor as effortlessly sophisticated. So, unwrapping a new collection called Rawls Sings Sinatra (Savoy), I was prepared for skillfully executed, caramel-smooth but generally uninspired professionalism. Since, though, I hadn’t heard Rawls in quite a while, little did I know that his trademark creaminess had grown so wonderfully rough around the edges. To borrow a favorite Sinatra quip, it sounds as if he’s swallowed a shot glass. The results are as satisfying as dusky bourbon over cracked ice. Though Rawls’ song selections favor the obvious (“Come Fly With Me,” “Nice ‘n’ Easy,” “That’s Life,” “Learnin’ the Blues,” “Summer Wind” and such), his gravelly interpretations are in no way derivative. Indeed, traveling the Sinatra high road, it seems Rawls has at long last discovered his inner Eckstine.