Young has ALWAYS Sounded like crap live, IMO.
And Bon Scott "made" AC-DC. Young carried the torch.
Don't get me wrong, Young was the perfect replacement for Scott, and I LOVE everything AC-DC ever did, but Brian has been done for a long time. Them cords is shredded.
My vote for a replacement vocalist, off the top of my head, is Phillip Anselmo.