Okay so I've been learning some Akatsuki the past 2 days.
Considering vorpal is essential for rapid cancels, I made an interesting combo conntection
(corner) 6C>5B>8B>8C>EX Piercing Legs>rapid>j.2C>EX piercing legs.
it does somewhat over 3.1k damage, It needs full meter to be done, but if unable, the grounded state helps to make distance on wake-up.
EDIT: Though I do realize you can overshoot and make the second armor piercing legs miss.