For the Cortege , use a Grand Jeu registration (Principal 8, Prestant 4, Doublette 2, Fourniture, Cymbale, plus reeds like Trompette and Clairon on the Grand Orgue). For the Litanie , switch to a Fonds d’Orgue (Flutes 8, 4, and a soft reed like Voix Humaine or Hautbois on the Positif).
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A: Yes. The piano version is the original. Dupré’s organ transcription adds pedal indications and registration suggestions, making use of the organ’s multiple keyboards and sustain. For the Cortege , use a Grand Jeu