This is completely unconfirmed yet, but someone in the trade chat was trying to sell an old BOE ring that was boosted to 865 Mythic +5 while retaining old level requirement.
This could easily be faked with a link generating script, but I think its worth checking it out. I would check it myself, but kazzak has a long respawn rate, so maybe if one of you gets lucky then you can either confirm or deny this.