The NCAA banned dunking from 1967 - 76. "The ban was intended to limit the dominance of Lew Alcindor, a 7'1 ⅜" UCLA sophomore who led his team to the 1967 NCAA championship."
As for the first UK player to dunk, perhaps it was Bill Spivey? He was certainly the first athletic, legit 7' footer to play for UK. In the 1951 NCAA championship game he had 22 points and 21 rebounds. It's a shame he was forced to leave school and banned for life from the NBA after being implicated in the point shaving scandal. He was never found guilty.
"I feel he would have been one of the top five centers of all-time had he had the chance to mature in the NBA." -- Joe B. Hall