McLain is still alive. Considering all the financial problems he's had since his career ended, I would think anything he had of value from his playing days was sold decades ago.
https://www.aaronsestatesales.com/sale/2623755
The Estate Of Denny McLain - Including Dennys massive sports collection. In this sale will be THOUSANDS of pieces of Baseball memorabilia dating from the 1930s - 1970s.
For decades the name Denny McLain has been synonymous with excellence in the sports field. His 1968 World Series win for the Tigers secured his legacy, awarding him the Cy Young Award, as well as the American League MVP, unseating Dizzy Dean to become Major League Baseball's first 30-game winner since 1934. The first weekend of October, Aarons Estate Sales, along with Mr. McLain, is bringing you a unique opportunity to enter his home and purchase items, including rare sports memorabilia, in an event estate sale experience. Denny will be live streaming his podcast show with Eli Zaret and Bob Page, “No Filter Sports”, and will be available to autograph purchased items, while the Aarons Estate Sales team brings you an amazing, not to be missed estate sale.