The principal source is the vocal score of the opera published by Joseph Dale in London in 1791. It gives the vocal lines with a keyboard reduction and occasional indications of instruments. This edition uses it as a particello, a short score from which the orchestra is rebuilt.
[List libretti, playbills, later editions and the 1989 Belgrade orchestration, with holding libraries and shelfmarks.]
Every note of Dale’s vocal score: vocal lines, keyboard reduction and printed instrument cues, all kept as printed.
The full orchestration and every reading that depends on it: instrumentation, part-writing, articulation and dynamics added to orchestral parts, the figures supplied in the overture and the realisation of the continuo.
The notes of Dale’s 1791 score are kept as printed. The orchestration is the editor’s; the opera is Storace’s.
The orchestration is scaled to the documented forces of Drury Lane in 1791 and draws on the scoring of operas Storace knew. The battle music of Act III, for example, follows the model of Grétry’s Raoul Barbe-bleue.
[Summary of the method from the dissertation.]
https://stephenstorace.com/sources.