Re-reading this thread just now, it's an interesting odyssey that began in the summer of 2008. A lot of people have contributed but most of the credit goes to Mark (chefmel) for sticking with it. Persistence pays off. Maybe I shouldn't have given up on stalking Morgan Fairchild after all.
Another thing that struck me is that Heaven Hill could be considered more the successor to T. W. Samuels than Maker's Mark is. Yes, the last remaining member of the Samuls family went on to found Maker's Mark, but it looks like Heaven Hill ultimately acquired what remained of the Samuels company's business along with several executives and several brand names. If that happened in the 1970s, Max Shapira would remember it, as would other current or (more likely) retired Heaven Hill executives.
My theory is that Charle DeSpain stayed close to the Samuels business even after he went to Heaven Hill in 1943, putting Heaven Hill in a position to acquire along the way any assets TW Samuels might wish to sell, perhaps also supplying them with whiskey and keeping them in business long after they stopped distilling. Sam Cecil worked at both Maker's Mark and Heaven Hill after leaving TW Samuels, but Sam was a production guy, not a business guy. He didn't pay attention to that sort of thing. DeSpain was a business guy. He's long since dead but there may be other people at or retired from HH who know about the final days of T. W. Samuels.