Toilets, Sinks, Showers, Tubs and Disposals - Laundry Sink Enamel (?) Repair

I have a 1965'ish free standing double tub laundry sink in my basement that I believe is made of cast iron with an enamel finish. The enamel in the tub that gets the most frequent use, including washing machine discharge, is deteriorating badly at the bottom of the tub, and most significantly at the drain. I'd like to try to repair/restore the enamel rather than have to replace it with all that would be required to break it up into pieces that could be carried out of the basement. Is anyone knowledgeable of any products or services that could be utilized to repair or restore the enamel in this sink? Thanks in advance for your help.

We had two dime sized chips in a tub repaired this year. Came to $100 + tax. Check your local yellow pages and you should be able to find companies that do this kind of work.