Reddit mentions of Plainsong Psalter

Assuming based on post history you're looking for 1979 prayerbook resources, I use the settings in the 1982 hymnal for most of MP and EP, and this for chanting psalms.

Also, hidden in the organist edition of the hymnal (but not the pew edition) is plainchant settings for noonday and compline, which is very annoying to me. You can purchase them separately here, but they often go out of stock/the algorithm sends them to unreasonable prices.

edit: if you have more questions I'm happy to answer them :)

OP: I started with the linked material here; it's an excellent resource and served me for at least a year or two.

I recently got the Plainchant Psalter for Christmas and am in love with it.