''Buddy: The Buddy Holly Story,'' a musical that has been running in London for 19 months and for six months in New York, will be one of seven presentations offered to Mechanic Theatre subscribers next season.
The announcement was made yesterday by Hope Quackenbush, managing director of the Mechanic, who added that two more shows are yet to be named. Previously announced were ''Nick and Nora,'' ''A Few Good Men,'' ''Lost in Yonkers'' and ''The Piano Lesson.''
The announcement took place shortly before Charles Strause, composer of the score for ''Nick and Nora,'' and Richard Maltby Jr., lyricist for the same show, gave invited group sales leaders a mini-concert version of the score for the show.
''Nick and Nora'' was to have had a try-out engagement at the Mechanic last year, but because of budgetary problems was not. Now, it will be the opening show for the 1991-1992 season. It is scheduled to begin performances on Sept. 21. The $6-million musical will remain at the Mechanic through Oct. 20.
Maltby and Strause did seven numbers from their new show, with Strause (''Annie,'' ''Bye Bye Birdie'') at the piano and Maltby doing most of the singing. A stuffed animal, looking like Asta, Nick and Nora's pet, sat on the top of the piano.
Maltby, who did the lyrics for ''Miss Saigon,'' said that ''Nick and Nora'' could be described as a ''comedy-romance-mystery-murder-musical.'' He added that the show is not a spoof of the Dashiell Hammett ''Thin Man'' stories. ''It is a true murder mystery with song,'' he said.
Joanna Gleason will be Nora Charles, and Barry Bostwick will be Nick. Christine Baranski, who once worked at Center Stage, will play the lead supporting role in the show, that of a Hollywood actress.