I saw Tong Gai acting as Hsia Wu's servant in the cave and not Yuen Wo Ping.

Alos, the art director is Chan Ging-Sam / (陳景森) and not johnson Tsao.
HKFA and movie credit confirm it.

Can anyone confirm and update?

Changed art director.

You are right with Tang Chia. Added. Yuen Wo-Ping is only a extra in the movie.

Thanks Michael