It might be easiest to use adhesive to secure a section of facsia to the front of the tray that will look compatible. Since the tray front is already broken, you don't have much to lose. There are resources at home improvement stores, on scrap piles or maybe even around the house that could provide a metal or plastic piece that could be cut to fit. Nobody will know the difference except you and your friend.
Also, if the rear portion of the tray has a flap that can be positioned flat or upward, I suggest keeping it flat. On my '52 Kelivnator, the cabinet temperature was way too cold with the rear portion of the tray adjusted to allow cold air from the freezer to fall into the fresh food section.