As New York City parents debate proposals to increase diversity at public schools on Manhattan’s Upper West Side, one example of integration is Success Academy, a charter school that faced stiff opposition when it opened in fall of 2011. Success Academy Upper West, on West 84th Street, roughly reflects the racial makeup of the area. With 443 children in kindergarten through fourth grade, the school was among the top performers citywide on state tests last year, according to city data.