Complex sentence: His final film appearance was as the famous Russian bass Feodor Chaliapin in the Technicolor film biography of impressario Sol Hurok, "Tonight We Sing" (1953); he sang a portion of Mussorgsky's "Boris Godunov" in the original Russian.
Split into simpler sentences: His final film appearance was as the famous Russian bass Feodor Chaliapin in the Technicolor film biography of impressario Sol Hurok, which was entiled "Tonight We Sing" (1953). During the course of this film, Pinza sang a portion of Mussorgsky's "Boris Godunov" in the original Russian.