Since the shinano was essentially a reconverted Yamato-class battleship we should create a new carrier from the Yamato hull...otherwise the Shinano would resutl too small to be realistic. However I know this might be hard...very hard.
Externally the Shinano was very similar to the Taiho
http://en.wikipedia.org/wiki/Japanes...ier_Taih%C5%8D
http://en.wikipedia.org/wiki/Japanes...arrier_Shinano
..so If it is not possible to create on from scratch we coud always use the model of the Taiho...