Knockabout (1979)

Brothers Little John and Big John make a living as small-time con men. When things go sour, they turn to a powerful man called the Silver Fox, only to find that he too is a con man who's playing them at their own game. Their luck is sure to run out soon, but lucky for them, they run into Fatty the Beggar, who proves that when it comes to the real power of kung fu, looks can be deceiving. ~ Cammila Collar, Rovi