China 9, Liberty 37

Already sentenced to hang, gunslinger Clayton Drumm (Fabio Testi) is given the opportunity to redeem himself by agreeing to murder obdurate prospector Matthew Sebanek (Warren Oates), whose refusal to sell his land is standing in the way of a railroad. Drumm agrees to the killing, only to find that he likes Sebanek, and likes his wife, Catherine (Jenny Agutter), even more. He doesn't do the hit but does give in to temptation, and is obliged to flee as both Sebanek and the railroad pursue him.