A drum smoker doesnt get hot enough to warrant hi temp paint.
No reason to burn out as it's already down to bare metal.
Yes you are lucky to have found a clean and bare metal drum. You just have to start building your UDS and then season it too. I might go find some orange and blue high temp paint for the outside thou. Heck even the money is right.
There is no need for high temp paint, however if you let your temps get away from you, say you don't get the lid on tight, it could reach temps that would burn the factory pain off. But if it where me I would just wash it and go to town on your build.