not making a comprehensive post (well, not right now), just noticed something - the New York Public Library really does list (... after a quick search; and Greene mentions this in his biography) a whole lot of mss of his music, don't they. I only just noticed... hrm. :)
Eric,
Do you think they may have the concertante work(s) premiered by Maud Powell?
I read about them in a reply I had from the Maud Powell society the other year and wondered what sort of works they were (i.e. romantic or a little more avant garde?) - I'm not aware of any (available) recordings of these works, apart from the Hyperion PC.
Best wishes
Richard
the collection at NYPL does have several scores/material of various kinds (reduced, full, maybe parts also) of Huss' violin concerto (Op.12) and I think his violin sonata also, I remember at least that was listed among the several hundred or so items there...