This is a general suggestion, mainly.
I guess it's fine that it belongs to this board
By the way, there are other Moderators (with definitely more experience), along with me, that take care of the forum
On the matter, I'm not really so acquainted with background music in the Mod, and I thus can't honestly answer.
As I don't remember correctly, are the credit songs you are referring to
Into the West and
The Last Goodbye?
If they are, I don't think they could be suitable (though they are greatly brilliant songs) since they are actual 'sung songs', while I believe the background music of shell maps should solely be instrumental music.
But, as I said, I don't have the proper knowledge to help you.
You might need an answer from the
Edain Team.
EDIT: I saw the posts on ModDB.
Yes, you are referring to the credit songs of each film, from
May it be to
The Last Goodbye.
I personally love those songs, but I don't think they are suitable for the reasons indicated above.