Well, GT did craft a jointed body for him, but I found it too skinny. Also not sure if it's still available, but I haven't looked too hard. Maybe somewhere online. And it has the attachment for the wing, which is cool.
I used a Jiaou Doll seamless body for my Sephi cuz I liked the muscle tone on it. Skintone match is perfect too. Only thing is that it required slight modification to get it to fit right. The neck was too small, so I added Saran wrap around the metal pole on the inside of the neck to thicken up the neck, which worked perfectly. Next was the ball-joint. It is too small to fit the head. This fix is up to your discretion. My Sephi is sleeping so he doesn't need to move his head, so I hot-glued it on there. I'm sure there are other ways. Maybe adding hockey/medical tape to the ball-joint would thicken it up enough to hold.
Here's my Sephi on Jiaou doll body JOK-12D-YS
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