I know it's not an upgrade, but I think about add two spanish ships: Principe de Asturias (112 guns) for 1st rate and El Glorioso, but you guys know, like Principe de Asturias for a new DLC (also more ships from Denmark and Dutchland)
http://www.laalcazaba.org/wp-content/uploads/2014/12/MAQUETA-DEL-GLORIOSO.jpg