I'd start at the Jazz Record Mart, 444 North Wabash. If they don't have it, they can get it or give you a reference to track it down.The JRM was founded by Bob Koester, founder of Delmark Records, who was a well known collector and producer in the blues field. I haven't been there in many years but if it hasn't abandoned it's legacy, it should be a great place.
If you decide to go there, come back and bring me up to date on it's current status.
- Mark