Ace doesn't have the support for it. I was once told, the correct way to sing tenor is to sing it like a bass, just higher.
Grin...I didn't say Ace would do Orbison well, just that he could try it. As a woman, I had high hopes for Ace in the beginning of the season. He's very good looking with a killer smile. So what happens? Not only does he turn out to be very effeminate, but he can't sing. Very disappointing. Very 2006, sigh.