Last July when I made a break in Paris, I started arranging a double choir mass from several a cappella choral works by Felix Mendelssohn. I have now completed the task and the mass is now on the Choral Public Domain Library at this page, and you can also listen to a Midi file here.Mendelssohn originally wrote several 8 part movements of the mass in German for Lutheran services: the Kyrie, Ehre sei Gott (Gloria) and Heilig (Sanctus), but he omitted the Credo and the Agnus Dei. I have left out the Credo, and for the Agnus Dei I found an 8 part setting of a Passiontide piece called Herr, dedenke nicht unswer. With the exception of the Kyrie which Mendelssohn wrote in the original Greek, I have substituted the German text for Latin, having also to tweak around the rhythms to make the syllables fit. For the Sanctus, I have also split it into two sections to make a separate Benedictus for extraordinary form of mass. All in all, it seems to work very well.
This was suggested to me by a member of the Birmingham Oratory choir, who had just come back from a choir tour singing Mendelssohn's German settings as part of a church service, that a Latin version could be made up. This is carrying on a long established tradition and practice in the Birmingham Oratory of reworking Mendelssohn's German and English anthems into Latin for use at our High Mass. Hence we sing Cum Natus Esset adapted from Da Jesus geboren ward at Epiphany, Sicut Cervus from Like as the hart pants, and Justus ut Palma on St. Joseph from a chorus in Paulus.