Syllecta Classica at the Classics Department of the University of Iowa is a journal for interdisciplinary approaches to classics and its related disciplines. In a 1997 conference transcribed in Syllecta Classica vol. 10, two opera libretti with the subject of Sulla are discussed, with an abstract, Seneca and the "Sulla" Operas of Handel and Mozart, available. Sulla is called "the tyrannical and nearly irredeemable figure."
The operas are Silla by Giacomo Rossi with music by Händel, and Lucio Silla by Giovanni de Gamerra with music by Mozart.
The conference as such is reviewed in Bryn Mawr Classical Review 2000.06.30: John Porter, Eric Csapo, C.W. Marshall, Robert C. Ketterer, Crossing the Stages: The Production, Performance and Reception of Ancient Theater. Syllecta Classica, Volume 10, 1999. Pp. xii + 282.
Mozart Libretto in English. Synopis.
Johann Christian Bach, at about the same time as Mozart, composed an opera also called Lucio Silla, with the same plot that Mozart used.