Here's an "origin" story of Fan Sai-yuk, Fang Shih Yu or as the dub pronounces it in this movie, Fang Su-yi, which is just weird to hear. Anyway, it stars Fei Meng as the hotheaded youth who causes a dispute between clans and ends up getting his father killed. His mother then makes him train and take special herb baths so he is invulnerable to weapons. After he nearly gets beaten to death by the two evil brothers he then gets his revenge during a tournament (a common plot for Fong movies).
I thought this was a more recent movie, but according to all my vast resources (the google) it was made in 1972. Finding an ad matte for it makes that seem more probable, but still, it looks great for a non-Shaw movie from that time period. The dubbing fits from that time as well, since there are several recognizable voices present.
Meng made at least three movies starring as the legendary Fong Sai-yuk, and his martial arts got better in each one. He also appeared in several Shaw movies, notably Five Shaolin Masters but probably more. His kung fu here is a bit imprecise, and doesn't much look like Hung Gar, but he's pretty decent. His Fang in this movie is really kind of a jerk who causes most of this trouble.
The great (and I mean that literally) Yasuaki Kurata is Iron Fist Tan, one of the villains and his martial arts are amazingly excellent. His kicks are precise as are his punches. He's also a great actor and truly makes the movie worth watching. He definitely deserved superstardom in this country. This reminds me I need to finish watching Fight! Dragon soon.
The movie is presented in non-anamorphic letterbox, and probably sourced from a PAL tape, as the colors change here and there. For the price of the set, one can't complain too much.