The following transcript is taken from ABC's special June 30, 1971 broadcast of "The Dick Cavett Show," during which former Navy Lieutenant John Kerry represented Vietnam Veterans Against the War. He was opposed by fellow Navy veteran John O'Neill, representing Vietnam Veterans for a Just Peace. ---------- MR. CAVETT: The fact is I don't have an opening monologue tonight because the subject of the show is quite serious, and I figured why make it more serious with one of my monologues, so I thought I would just start in. You know, I guess, who my two guests are tonight: John...