Fill a large pot with lightly salted water and bring to a rolling boil. Stir in pasta shells and return to a boil. Cook pasta uncovered, stirring occasionally, until tender yet firm to the bite, about 12 minutes. Drain well. Separate shells quickly so they do not stick together or tear.
Combine chicken, celery, bell pepper, almonds, green onions, and relish in a large bowl. Mix mayonnaise, sour cream, lemon juice, curry powder, zest, salt, and lemon pepper together; pour over salad and toss.
Stuff each shell with a portion of the salad, arranging them in a 9x13-inch baking pan as you go. Cover and chill for at least 30 minutes or until ready to serve.