My understanding is fuzzy on this (and on a lotta things!;-) but wasn't there a plan to remove the existing clock, departure boards and kiosk? I know it sounds crazy, so don't freak out just yet...
In my vague recollections, the board would then go above the existing VIA ticket booths, and don't ask me what would remain in the centre of the Great Hall.
(I believe there has been a clock and some kind of booth in the centre of the 'Ticket Lobby' for almost if not all of the years since it was completed.)
If anyone can scour through the older plans to see if there are hints, that might help.
I for one cannot recall ever seeing an "artist's fan--" I mean "rendition" of a completed Great Hall.