I don't see why you would need more than about 20# of Kast-0-Lite, 3' of Inswool and a pint of Metrikote.
Again, I suggest that you
Check out the Build a Gas Forge and the Ribbon Burner attachments on the Forge Supplies page at www.WayneCoeArtistBlacksmith.com.
Let me know if I can help you.