Home Distiller

I just bought a 15-gallon steel drum that I would like to use as a brew pot for brew-in-a-bag mashes. My plan is to sandblast it to remove the paint and any liner and take it down to the original steel. I do not believe this is a stainless steel drum. I also intend to add a spigot. I use a powerful propane burner and am concerned about rust and corrosion. I plan on finding a scrap piece of metal to try and protect the drum from the fire. Is there anything I can do to protect the inside of the pot from rusting out? Any other suggestions?

Carbon steel is not an approved material for a boiler. The acid in the mash and backset with eat it up quickly. It needs to be Stainless Steel.