If you want to go very simple, pick up a copy of the Mundelein Psalter. They have very simple psalm tone settings of the entire Breviary, including all the Gospel Canticles.
Given the structure of the Benedictus, it fits more readily with psalm-tone-like settings rather than a through-composed melody or strophic form, so if you find one of those, it probably paraphrases the text.
I don't know what kind of musical forces you're working with, but I've always liked Charles Villiers Stanford's setting of it from his Morning Service in C Major. I don't think you can find the score online, though. You'd likely have to purchase it.
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