If you can make good biscuits, then you can make good sweet-potato biscuits. Substitute mashed sweet potato for a roughly equal amount of flour. Biscuit dough can easily handle a one-to-two ratio of potato to flour, and probably even one-to-one.
Your biscuits will be very tender.
Many kinds of bread, actually — both quick breads and yeast breads — benefit from some potato. I think of this as German thing, though I have had sweet-potato biscuits in African-American restaurants.