Downey From Dallas: It took intervention by a judge, but Morton Downey Jr. was allowed to broadcast his nationally syndicated radio talk show Monday from the former Texas Schoolbook Depository in Dallas, the spot where Lee Harvey Oswald fired at President Kennedy 29 years ago. His program focused on the assassination and conspiracy theories and included an audio tour of an exhibit on the sixth floor. County commissioners had moved to block the broadcast, saying they feared exploitation of the exhibit that preserves the sixth-floor perch from which Oswald shot Kennedy on Nov. 22, 1963. Downey cited the First Amendment in going to court to get permission to broadcast from the site. "This is a beautiful exhibit that took a lot of guts for Dallas to put together," Downey said. "My intent is not to exploit it, but to open the door for the whole world to appreciate."