Angel on my shoulder

 Gangster Eddie Kagel is killed by a trusted lieutenant and finds himself in Harry Redmond Jr's special-effects Hell, where Nick/The Devil sees that he is an-exact double for a judge who Nick doesn't approve of. Eddie is agreeable to having his soul transferred to the judge's body, as it will give him a chance to avenge himself on his killer. But every action taken by Eddie (as the judge) results in good rather than evil and, to Nick's dismay, the reputation and influence of the judge is enhanced, rather than impaired by Eddie. And Eddie also falls in love with the judge's fiancée, Barbara.