I realize this is quite a long shot, but does anyone here have access to a volume printed at Ratisbon in either 1863 or 1864 titled: "Officium et Missa Immaculatæ Conceptionis Beatæ Mariæ Virginis Gregorianis Modis aptata"? It is apparently a set of chants for the feast of the Immaculate Conception composed by a certain Gratiliano de Petro for the office and Mass promulgated by Pius IX in 1863 for the feast. The volume is only in two libraries according to Worldcat, but bizarrely it shows up as "unavailable" on Amazon, so I wonder if perhaps a copy circulated at some point in the recent past!

Here is some information from a contemporary source about the volume: