One of my favorite films EVER is Sergio Leon's masterful "Once Upon a Time in the West" (1968). The uber- prolific Ennio Morricone's score (pronounced EN-nee-oh More-uh-KOE-nee) is top notch too. The little harmonica lick Charles Bronson repeats trough the movie always stuck with me.
BUT, studio group Black Light Orchestra (B.L.O.) manages to mix both of these elements together to an awesome effect on their extravagant disco production (ala Dennis Parker's incredible "Like An Eagle") take on Ennio Morricone tune. The way the chords move around the melody is sublime. Good chord changes, I'm always a HUGE sucker for THAT. Flashy disco of the highest order.