Place the 2013 iMac motherboard inside a 2012 iMac.
Place the 2013 iMac motherboard inside a 2012 iMac.
It could be possible, but I'm unsure if all the mounting points are in the same spot. Removing an iMac, particularly the 2012 and newer ones, to swap out a logic board isn't very enjoyable, so I wouldn't go through with it just for the sake of it.