Get a copy of "The Helio Courier" from Frank Joseph Rowe, McFarland publishers. Some details here, but no drawings.
Call JAARS in Waxhaw, NC. They have (had) the largest fleet of Couriers and still fly Old Number One. They regularly rebuild wings and probably have details you'd need. Try 704-843-6172.
If you have general interest in high-lift, STOL, slats, etc. maybe I can help you as I have been around these things for 30 years. Contact me offline, email@example.com
President, EAA1114, Apex, NC