To launch its new Chunky Chicken Pot Pie, KFC Corp. next Wednesday will assemble the largest pot pie in history in New York. Workers will begin creating the 12-foot-round pie in Bryant Park at dawn. The festivities include a kick-line of dancing peas and carrots and a 75-foot chicken balloon hovering over the park. KFC will hand out samples of the new product to onlookers. KFC is backing the launch with a $10 to $15 million campaign from Young & Rubicam, New York, breaking Monday.