I'm wondering if a little creative machining might be done on a somewhat similar 8 lug drum from a different make or year truck to make it fit the hub? A lot can be done with a spacer or some center hole modification, since the 8 lug wheel bolt pattern is shared by several makes. It might be possible to make a Ford, Dodge, International, or other make drum fit. The part doesn't know or care what it's bolted onto. Even a complete drum, backing plate, and shoe assembly might be possible to adapt.
You'll need to remove the spindle nut outboard of the bearing as well as removing the nuts that sandwich the drum between the halves of the hub to remove the drums.
Jerry