I guess that the full score of this work was first published by Fondazione Rossini in 1999:http://www.fondazionerossini.com/shop/?p=185
Such edition includes two volumes (total 942 pages) plus a critical commentary of 220 pages. Price Euro 155. Due to "urtext" (and possibly "editio princeps") provisions this edition is copyrighted in the EU until 2024, and thus not eligible for publication on IMSLP until then.
A vocal score with piano reduction obtained form the above edition was published by Ricordi in 2006 (523 pages, priced around 60 - 75 Euro at some online stores). A piano reduction is usually eligible for full copyright, not just for "urtext" or "editio princeps" protection, so this edition will still be under copyright for many years.
If the above is correct I think that, due to copyright reasons, nobody can take this task in the near future. Thank you anyway for the proposal.