If he’s got the forces, here’s an 8-parter by Crecquillon: score at IMSLP
AR Editions publishes this 6-parter by J Maillard, VIDIT DOMINUS PETRUM ET ANDREAM:
http://www.areditions.com/arfiles/product_images/R096Y003_samples.pdf
And, although the style may be more challenging, there’s Dufay’s APOSTOLO GLORIOSO:
https://www.allmusic.com/composition/apostolo-glorioso-isorhythmic-motet-for-5-voices-mc0002393728
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