Complex sentence: In 1957, Smith recorded "So Long, I'm Gone", a song written by Roy Orbison, and it did become Smith's biggest hit at Sun, peaking at No.74 nationally ("Billboard").
Split into simpler sentences: In 1957, Smith recorded "So Long, I'm Gone", a song written by Roy Orbison. It became Smith's biggest hit at Sun, peaking at number 74 nationally ("Billboard").