The score is in the book
Engel in der Orgelmusik
(Angels in the Organ-Music)
Butz-Verlag, Bonn (GER)
I made the first version yesterday with the Cavaille-Coll-Organ St. Eucaire http://www.contrebombarde.com/concerthall/music/29013
Auke asked in his comment, how that will sound on a larger organ in a larger space.
So I played it again today on the Sonnenorgel and I found a wonderful registration with using the fine Clarinette in the swell for the mens-choir.
Thank you, Auke, for this challenge :-)
...and friendly greetings!