Brush both sides of chicken with barbecue sauce; grill or broil about 5" from heat source 6 minutes per side, or until juices are clear.
Meanwhile, in a large bowl, combine lettuce, tomatoes, 3/4 cup cheese, pepper, corn, black beans, olives and green onions; mix well.
Combine dressing, chili powder and cumin; mix well.
To serve, divide lettuce mixture onto 6 serving plates.
Cut chicken crosswise into 1/2" thick slices; arrange over lettuce. Drizzle salads with dressing and sprinkle with remaining 3/4 cup cheese. Chicken may be cooked, cooled, covered and refrigerated up to 1 day before serving.
Reheat chicken or served chilled.
Lettuce mixture and dressing may be prepared separately, covered and refrigerated up to 4 hours before serving.