I dont like it. Keep in mind authentically signed Elvis albums especially in the 70's are probably rarer than any other type of Elvis autographs. Any items sent backstage were usually signed by his father or friends.
I don‘t think that this is real. This is not Elvis handwriting. And the place -where it's written- doesn't fit in my eyes either. And Steve is right, most of the items sent backstage were usually signed by his bodyguards.