On the subject of getting copyright approvals and permission to
reproduce, music can be an absolute mess, as often the copyright holders
don't know they hold it. In the case of sheet music -- and four items
I need to reproduce for my upcoming book "Let The Other Guy Play It!",
the pictorial history of coin-op mechanical music in America -- I got
so many runarounds I got dizzy.
I did learn that there are two copyrights for sheet music; the music,
and the artwork cover, and often they are held by different sources.
The publishers changed ownership so often it is difficult to track down,
although ASCAP will usually have the latest copyright holder name for
the music (but not the covers).
If the printed piece is 75 years old or older you are clear, but a day
newer at the time of usage, and you aren't. In the case of one sheet
I have contacted 16 sources by mail and telephone, always using certified
letters to assure date of delivery and my serious attempt to follow the
rules. Twice I got permission, with a follow-up letter saying they
didn't really own the rights, that someone else did.
In cases like that, proof of a serious attempt will go a long way to
protect your position. But, as I said originally, it's a mess.
So happy hunting.