There are insufficient bulkheads to be repaired to have someone specialise in this work. There are any number of people with the skills to do it but it comes down to if they are prepared to do it and will you be prepared to pay the price. I'd look at panel beaters and sheetmetal fabricators for a start.

There are a couple of threads with photos of how to go about it where people doing their own restoration have done a good job of cutting out the rust and replacing it with sound metal.

Good luck