This A/ is authentic, neumes from H, but melody as found in PsM following a slightly different tradition, retained to be able to assign it the peregrine tone.

Added "Deo" in the end - in this instance I think matching the BR is important.

From 1916 LN draft

I really want to add the si bémol like Sandhofe did, and use this A/ with the Tonus Peregrinus