Im confused...Are you sure? Reading this guide and it seems like you don't need clean 70 stones.
https://web.archive.org/web/20120811220422/http://forum.top.igg.com/viewthread.php?tid=91798&extra=page=1&filter=digest
"PLEASE NOTE!!!: The boss stones do not need to be unfused for this process to work!"
EDIT:
It's okay. I found my answer.
http://pirate.mmosite.com/guide/death_set.shtml
"Requirements to Upgrade
Your black dragon piece / Level 70 boss stone or fusion gear with boss stone inside
1 million gold is required to upgrade
The specific item that's required for your class
You can still upgrade when it is fusion into the appreal armors
When upgrading with appreal fusion armors, your armor will be gone, but your gems will stay (The Level 75 death set has no effectiveness %)"
Looking at at this site
https://mordo.info/npc/view/npcid/30095/
Says you only need lvl 70 boss stone, their soul and 1 Million gold to upgrade for a death set piece.