On the topic of dedication and rededication, the cathedral choir will be singing this "Stetit Angelus" (the offertory for the feast) for SATB. It is one of Msgr. Ronan's better pieces.
Yes, the LU has Missa II and Missa III listed for that. Technically, you can sing whichever Gregorian ordinary you wish, the lists are just suggestions. You can even pick and choose from one ordinary to the other. It is, however, a venerable practice to observe those suggestions whenever possible, and sing entire ordinaries intact.
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