We have booklets of it in our monastery, but I am not sure what the original source is from, as we are cloistered but without a vow of stability and so therefore can be, and are sent to different monasteries ever 2-3 years, thus we have lots of things without knowing where they came from because of frequent change of sisters... We have a booklet with all the Gospel Canticles (Magnificat, Benedictus, Nunc Dimitis) which has each G.C. in the 8 tones. Previously we had just been singing the antiphon in directum when we wanted to chant a different tone, and on feasts use the tone iiia...

You can sing any text to each of the (more than eight) psalm tones. But which one you actually use depends on the antiphon that is sung before and after.

For Compline, Salva nos is the traditional antiphon, but the 2015 Ordo Cantus Officii offers alternatives: Vigilemus omnes, Gregem tuum, Lucem tuam and Pacem tuam.

These alternatives are not all of mode IIIa; IVe and VIIIg are among them.

Gregem tuum can be found in Abbazia di Praglia, Salterio Corale (2015), 316. The other antiphons have not yet been published in modern chant books. The transcriptions by Joerg are, in some cases, questionable.