Complex sentence: He toured the summer stock circuit as El Gallo in a production of "The Fantasticks" and later replaced Ken Howard in the Broadway musical, "Seesaw" (1973) opposite Michele Lee.
Split into simpler sentences: He toured the summer stock circuit as El Gallo in a production of "The Fantasticks". In 1973 Gavin replaced Ken Howard in the Broadway musical, "Seesaw" (1973) opposite Michele Lee.