This is tough because no actor is up to the Shang Chi role. But I can imagine stuff:


Shaw Brothers Version:
I'd give a strong thought to using a mustacheless Ti Lung or "Tan Ming" from "Ten Tigers of Kwantung" in the Shang Chi role with the Venoms playing any combination of Si-Fan or resurrected Dacoit warriors. I'd put either Wong Lung Wei or a whitehaired Lo Lieh (e.g. Fists of the White Lotus) into the Fu Manchu role and make Fu Manchu a supreme kung fu fighter. Give me Chen Kwan Tai for Cat.


American version:
Anthony De Longis for Zaran, Robert Carradine (David's father) as Fu Manchu, David Chow for for handless Li Chun, Angelique Jolie with dyed black hair as Leiko Wu, and Jason Scott Lee for Shang Chi.


Bruce Lee version:
Lee as Chi, Bob Wall as Black Jack Tarr, the girlfriend from Chinese Connection as Leiko Wu, Dan Inosanto and Chuck Norris as Si-Fan, Bruce Li as Shang's evil twin brother, Jim Kelly as Shang's training equal "Midnight".


Comedy version:
Jackie Chan as Shang Chi, Sammo Hung as Li Chun, white-haired Huang Cheng Li as Fu Manchu.