Sorry not to familiar with your model, but could you get a memory foam mattress and cut it to fit your needs. When we were looking we found that we needed a odd size mattress and the easiest and cheapest thing to do was to cut a little of the length off of a standard size memory foam mattress to make it fit. We were able to afford a better mattress without having to spend extra on a special size.
Other option would be a custom mattress place like "the Original Mattress Factory" (several stores in the east). They make their mattresses on site and I know of some who have asked for a custom size and it didn't cost them hardly any more than a normal mattress.
