We had a pink cast iron enamelled bath (really NASTY pink!!!) when we moved into our house. Got it resurfaced by a professional, think it cost about �100 or so and they made a cracking job of it and finish looked as new. But you have to treat it very carefully regarding what cleaning projects you use and it is more prone to chipping scratches etc. As for drainhole they simply masked it off and sprayed round it, on hindsight would have been better to slacken all drain pipes and taps etc to get better overall coverage, also something to keep in mind if you were to change taps at a later date.