Honey in His Mouth — Lester Dent

If you were small-time grifter Walter Harsh, recovering in a hospital with a broken arm, you'd listen to a proposition that could net you a cool $50,000 for impersonating the South American strongman you resemble. You'd pay attention when the dictator's sultry mistress started putting the moves on you. And in the dead of night, when no one was watching, you might just hatch a plot to get it all for yourself: the money, the girl, and the stash of stolen loot she's conspiring to spirit out of the country...