I also did what Fireguy did, when I converted an old freezer. If the inside is porcelain (which I bet it is) you are good to go. If it is in fact paint, then yeah you'll need to remove it. You can tell by trying to drill a hole in the material. If you center punch, and a small fleck of ceramic type material chips off - porcelain. If not, it's probably paint. If still not sure, go ahead and try to drill it, porcelain is very, very hard to drill. You'll know. If I knew how to link to past threads, I'd pull up my thread with pics of mine.