I had mine (food drums that had bags of food dye in them) sandblasted. That takes all the junk out of it and off of it. I did a burn of charcoal in it and then cooked a butt for six hours. That left a nice oil char in it that has lined it every since. No rust and no cleaning after that, just lots of cooking. I would say that these pristine drums would be as easy as that for you as well. Cooking a chicken in it when you season it is a good idea. Mixing a little bit of grease from the bird with that char smoke gives you a nice season on the inside of the drum, then the trick is to cook often which won't be a problem once you taste product from a UDS. It is the way to cook and the coolest thing you will ever make. We use ours every single week no matter the weather or the temp. I did three racks of ribs last weekend in four and a half hours and it was 5 degrees outside at the time. Absolutely no problem keeping it at 250 even with two of the vents closed. They are simply cooking machines.
Ok finally finished my Charcoal Basket... (minus handle)
I used a 4ft x 4ft section of expanded metal. I cut it down to 1ft x 4ft formed a cylinder and used stainless steel bolts nuts and washers. For the bottom i cut a round piece and used steel wire to tie it together. ( weld free basket ).This was actually easy if you dont over think it.