Would any writer or musician actually want someone finding and publishing a first draft? I think most would feel more like Anne Lamott, who says in Bird by Bird,
"But the bad news is that if you're at all like me, you'll probably read over what you've written and spend the rest of the day obsessing, and praying that you do not die before you can completely rewrite or destroy what you have written, lest the eagerly waiting world learn how bad your first drafts are."
Even so, I love the idea of a lost work being found, even if it was a first draft. And I love it that the first draft was "very Beethoven."