Karl Towns, a 6-foot-11, 230-pound rising sophomore from St. Joseph (Metuchen, N.J.), is living a dream this summer. He is playing with the Dominican Republic national basketball team (his mother was born there) as it bids for an Olympic berth. Not long ago he played before 16,000 fans as his team defeated Puerto Rico 80-72 to win a 12-team tournament featuring professional teams from Central America. The victory provided him with his first of what probably will be many gold medals. His teammates include NBA players Al Horford of the Atlanta Hawks and Francisco Garcia of the Sacramento Kings along with several former Division I college players. AND he is coached by John Calipari, who guided Kentucky to the latest NCAA basketball championship.