I managed to pick a decent looking one up from the local tip, but it has had special meth spirits in it so im VERY reluctant to start cutting it up and im sure storing such chemicals wouldn't be good for cooking food in.
Im guessing it would need to be food grade or at least not been used to store chemicals, oils etc
The one I used for my UDS had metho in it, I took the bung out and let it breath for a week or two, mad sure there was nothing left in it, then cut the top out.
Gave it a good burn out and she was all good. Wasn't even lined, was raw inside, which saved me heaps of work! Also, you can use metho as a fuel to cook food, so shouldn't be an issue to use the drum, I've had no issues with mine, thats for sure.