Ed,
I would call Dave Kiff at Pacific Tool 541 826 5808 for a reamer.
If you want a .404 I think the Dakota version has a lot going for it. You get a SAAMI-standard cartridge with at least some factory ammunition. The .404 Jeffery is not a SAAMI standard by the way, and there are differences in bore diameter and other cartridge dimensions in the ammo that is available.
The .404 Dakota is an excellent killer of dangerous game, including elephant.
jim