OBC wattage is measured in kW, not kWh.
It would probably be near impossible w/o a LOT of other things needing swapping, esp. since it moved from the back of the car (under the hump) to the front on '13+ Leafs.
See 1st 4 URLs at viewtopic.php?p=576111#p576111
. There are also coolant and high voltage lines running from the front of the car to the back which are n/a on '13+ Leaf. The motor (which is part of the PDM stack) is also different on '13+ Leafs from prior ones.
Your only semi-easy choice is the Brusa charger: https://www.mynissanleaf.com/viewtopic.php?t=12323