I’ve never gone after walleye on the fly personally, but I guide I know back home (WI) swears by simple rabbit-strip leech patterns. He would probably know since he holds the line class WR for the species. I don’t know about MI, but wild leeches in WI tend to be brownish, so I would recommend a grizzly-tan colored leech pattern. I would definitely go w/ a pretty heavy sink-tip line. Let it get down in the water and slowly strip it in. They are almost always light biters so you’ll have to keep the line slack free to feel the take. Good luck.
Taylor