RE: Midwest Malibu .40
My best guess as a place to try would be Uncle Willie's plans. I have gotten a little crosswise with him because I challenged him for selling plans copywritten by other companies. He has been banned by RCU and Ebay as well as other sites and some ISPs because of copywrite violations but he does have some plans for long gone airplanes. I copywrite is good for about 85 years so you can see why the legalities are a mess when a design o company has been gone for decades.