It was included in his first collection, Ashes, which was published in 1978 by North American Liturgy Resources (ref).
It appears that sheet music is availble in the Ashes guitar accompaniment book which is still in stock with SheetMusicPlus (link below - to be confirmed that the book really has scores for all items on the recording).
Small group and congregation - light keyboard and percussion backing:
Another small group and congregation - light keyboard and percussion backing:
LyricsPeace I leave with you my friends my friends,
and I am with you till the end.
Lamb of god you take away the sins of the world,
have mercy on us OR grant us peace.