Trying to get conversions for body pillows.

I need help I have a dakimakura body pillow 160x80 and its very shitty it has stuffing in it but the case is made of cheap fabric that has ripped. Im searching for either a completely new insert that isn't garbage or just a case to transfer the stuffing. However the measurements seem difficult to find if anybody has knowledge or can help point in a good direction that would be great. I've looked from daki sites to Amazon just to find what I am looking for but can't find it