John McGlinn was born in Bryn Mawr, Pa., and grew up in nearby Gladwyne. He was a graduate of the Episcopal Academy in Lower Merion. A self-taught pianist, he studied music theory and composition at Northwestern University, from which he graduated in 1976.
Hemoved to New York and, caught up in the renewed interest in American songs performed in period style, recorded "Songs of New York" for Book-of-the-Month Records. For the Houston Grand Opera, Mr. McGlinn embarked on what would become a thorough overhaul of "Show Boat," which had been revised, and shortened, multiple times since its premiere in 1927. Consulting archives at the Rodgers & Hammerstein office and the London offices of Chappell Music, he pieced together a partly restored version that, after touring the United States, ran briefly on Broadway in 1983.
Later, after integrating material from the rediscovered Warner Brothers archives, he supervised a recording of the complete musical, with Frederica von Stade, Bruce Hubbard and Teresa Stratas in the principal roles. It was released in 1988.
After Mr. McGlinn presented three little-known Kern musicals as part of a Kern centennial festival at Carnegie Hall in 1985, EMI signed him to produce an album of George Gershwin songs with the soprano Kiri Te Kanawa ("Kiri Sings Gershwin") and a companion album of Gershwin overtures, performed in period style.
He later supervised the recording of restored versions of "Anything Goes," "No, No, Nanette," "Annie Get Your Gun," "Brigadoon" and "Kiss Me, Kate."
"He made it possible to hear what these musicals really sounded like," said Larry Moore, an orchestrator who worked with Mr. McGlinn. "He was adamant about authenticity. He felt that the American musical theater should be treated as seriously as opera."
In 2001 Mr. McGlinn, with backing from the Packard Humanities Institute, began restoring and recording the complete works of Jerome Kern and Victor Herbert, but left after a year, seized with the desire to conduct Wagner, a lifelong obsession.
Mr. McGlinn's most recent project, for the theatrical publisher Samuel French, was to restore the original orchestrations and previously lost dance music to the 1954 Broadway version of "Peter Pan." The match between restorer and project made sense.
The New York music theatre and opera circles knew about John's being gay. He was never married, never dated women or had children. John was estranged from his older sister- and after his mother died, his younger sister and brother. John's mother, in her will restriced his trust fund, unlike those of his siblings, because he was gay. John was later able to break that restriction.
He was found dead in his apartment on Feb. 14, 2009, and it was estimated that he had been dead for three or four days. It's believed the cause of death was a heart attack, but close acquaintances suspect possible suicide. He is survived by several sisters and a brother.