It took some time but I now have a Japanese New 3DS LL with a North American motherboard. Was finally able to bring my original Ambassador Certificate to it. : r/3DS
3DS LL Nintendo 3DS LL XL Console Only Japanese Edition Various Select Colors | eBay
Japan: Two Pokemon New Nintendo 3DS XL's Announced - My Nintendo News
New Nintendo 3DS XL LL Super Famicom Edition Console Box Japanese ver [BOX] | eBay