If you haven't seen the Haunted Mansion Holiday at Disneyland, that's exactly what they do with the singing busts in the Graveyard. They turn them into singing Jack-o-lanterns. (Though they're not singing Grim Grinning Ghosts)
Oh my gosh tht is so cool... My BIL would love that, he has spent thousands of dollars on his display and it covers his whole yard and garage and this would be so cool for the stairs.