The Mantle appears good. Not as familiar with the others, but they appear okay from my cursory knowledge. I have seen this pose signed authentically several times before.
The Killebrew and Mantle look fine. I have Mays signed items, but haven't really looked at them that much.
Ted, this is a strange one. the mantle looks great. Mays is all over the place, so he is hard to really authenticate for me, but the killebrew is uncharacteristically messy. usually you can read virtually every letter. But the H and K look good. the other thing that is concerning is that all three signatures are on the same line, and are the same size.
Great photo! All sigs are authentic