I have never encountered this phenomenon as the replacement forends I purchased for my 500 and 590 were model-specific.
The item you linked to says that it fills the gap for Hogue forends that are 6 3/4 inches long. Measure the forend you have now and see if it is that length. If it is shorter then the spacer you linked to will not help without adding something else to make up the distance. If it is longer then you might have to cut or shave the forend or the spacer.