Having owned one of these, if you want to shoot Fuji pack film with their adapter, it would take some revision to the camera as in modifications to the back to mount the adapter and perhaps the ground glass as well for focus; If possible at all. If you had a wood shop and were very creative you might pull it off, but seriously it's not worth the effort unless your committed to using only that film (for how long an undetermined amount of time?) with that camera.
That being said, your option is to cut your own film (cheapest) or buy any stock you find, whether thru Ilford's special order, Ebay, or perhaps Freestyle.
Conversely, there has been one example to my memory where the back was modified to accept a 4x5 back. I have no idea who did it or if instructions were provided and if in reality you actually got a 4x5 image area. The adapted back would have to stand off the camera back somewhat since the internal gate is so small; Or you could just shoot it and get the smaller 3x4 image without cutting film or buying more expensive stock. I myself looked at the overall possibility of adapting a 4x5 back, sans definitely needed additional GG focus work for that top focus ability, and found that one would effectively wind up with the back protruding beyond the sides if one were to use a back off a Graphic. For the cost of such cameras, it's just not worth it. Perhaps tho just creating a 4x5 adapter to easily lock on the back of the camera and to mount a easily available 4x5 Graphic back would be the way to go?