by Gaetano Donizetti
Opera d'Oro has released, without a libretto, a recording of a May 14, 1969, performance of Belisario at the Teatro La Fenice, Venice, with Leyla Gencer, Giuseppe Taddei, and Nicola Zaccaria, conducted by Gianandrea Gavazzeni.
Donizetti Belisario @
Libretto in Italian of Belisario
Donizetti Belisario at
The Opera d'Oro recording can be ordered through and through   Samples of the recording can also be heard at the amazon site.  To me the sound quality is acceptable for a "live" recording from the 1960's.
Belisario recordings at
Belisario, Zampieri, Bruson, Teatro Colon, Myto Records:45301,