Haru, Here are the tunes I was thinking of - they are all found in the Hymnal 1940, used by the Anglican Catholic Church and other traditional Anglicans. Many of the tunes had previously been published in 'Hymns Ancient and Modern' or 'The English Hymnal'

Stabat Mater - Either the Mechlin Plainsong (Mode IV) or the tune 'Mainz' taken from the Mainz Gesangbuch of 1661 (Hymn 76)

Come thou Holy Spirit, come - The Plainsong Sequence from the XI century (Hymn 109)

O sons and daughters, let us sing - The French melody, O Filii et Filiae (a XV Century tune (Hymn 99)

Brightest and best of the sons of the morning - The tune entitled Morning Star, by James Harding, organist and choirmaster of St. Andrew's, Islington, London (Hymn 46)

For Blessed Quitness, I was thinking of the tune sung by Lucy Simpson, Peter and Mary Alice Amidon, and Rock Creek on the Folk Legacy album, 'Sharon Mountain Harmony'