Around the time of Clambake, there were other actors who could fit the role model to Elvis better than Brando. At the time, Brando's career wasn't so successful. After the stardom in the late 50's, he did just another blockbuster, "Mutiny on the bounty", in 1963, after a decade of commercial failures. He just recovered its public ant critical acclaim with "The godfather", 1972/73.
In the other had, the beggining of Elvis movie career coincided with the first peak of Brando's popularity. So maybe this is why the Colonel had chosen him as as=n example to be followed or surpassed.
