Byrd Sacerdotes Domini ... at CPDL for free.
The edition by David Fraser is authoritative. The James Gibb edition is transposed up a whole tone but has a keyboard reduction of the choral score.

Praglia's Tu Es Sacerdos is very manageable.

Sicut Cervus - Palestrina
Haec Dies - Byrd
Jubilate Deo - Hassler
Cantate Domino - Pitoni
Laudate Dominum - Mozart
Animae Christe
O Bone Jesu - Palestrina
O Sacrum Convivium

I Sat Down Under His Shadow - Bairstow
Alleluia - Randall Thompson
O Sacred Feast - Willan
And He Shall Purify - (MESSIAH) - Handel

Here's another vote for "Sacerdotes Domini" by Byrd for an ordination Mass.

I also recall a rather nice "Tu es Sacerdos" but for the life of me I cannot think of the composer.

This is taken at a rather quick pace. Many do it more introspectively, However it's done it is the work of an inspired master. One often hears the alleluyas done with the five syllables which we discussed in another forum conversation. Try it sometime - it very may well have been done that way by Byrd: al-le-lu-ee.ee-ya.

Chris -
As you are well aware, it all depends on the room, the weather, the spirit of the moment, the spot in the liturgy, etc., not to mention your voices. I did think the above recording (which seems to be at Washington's Cathedral of SS Peter and Paul) was rather quick, even hurried - and it showed in their diction and the sloppiness of series of quavers - even moreso at the two semiquaver ornaments and the places where the polyphonic texture is most complex. On the other hand, it did have a 'jolly good' spirit about it!

In a live room I might prefer a tempo of approx give or take 80 - even less in dream acoustics.
In a less desirable acoustic I might go up to 100 or more.
It really does all depend on acoustics and the spirit of the moment.
My feeling about this motet is that is 'joyfully introspective'.
Others have different, and equally valid, approaches.
What's yours?
Or anyone else's on our forum?

I once took a choir on an outing to the two Spanish missions at Goliad (Texas). The larger one is a state park, and the smaller is still used by the Church (the wall painting behind the altar features Gabriel with six toes on one foot). We sang in the larger one and started out with Viadana's Exultate iusti. We began with our usual almost brisk tempo, and before we finished so much as the second measure we were so far ahead of the room that we had immediately to reduce our tempo to the snail's pace in order for the music to be intelligeable.

Here is a somewhat more relaxed reading of the Byrd "Sacerdotes Domini" by the Guildford Cathedral Choir under Andrew Millington

https://www.youtube.com/watch?v=Bvnu9KwotCA

Choral resources are limited. There are time constraints also as the ordination will be on October 26th. I take over on Sept 20th, so not actually in post yet. Choir of approx 15, at present no basses, but my husband, who is one and ex KC Cambridge, will be coming along with me. Not all the choir members read music. I fear the Byrd is a bridge too far at the moment. The Kreutz seems a good choice. I'll look at some of the others also; thanks for all the suggestions. Something simple but well done is the aim.