The next generation of 737 is really good. It's got better engines, the winglets for improved efficiency, and all that jazz. https://en.wikipedia.org/wiki/Boeing_737_Next_Generation

Unfortunately it wouldn't make a good bomber because of the basic layout of the plane. Compare the overall top-view layouts of the 737 vs the B-52, paying special attention to wing attachment points and where the bombing bay is, and you'll see what I mean.