The two-headed Hong rainbow dragon might be particularly difficult to adapt to the human form and still make appealing.
It's a basically a snake with another head instead of a tail. So, a Meiling with two heads on her shoulders, or a dragon-headed tail?
You could make both of her hands into dragon-heads, but that would give her three heads, and the Hong is supposed to have the usual four limbs of a Chinese dragon, so that doesn't work at all.
Going whole-hog with Voltron/GoLion-style heads for hands and feet (plus tail) would be far more suitable for the Orochi than the Hong.