To clarify your request:
You want someone with the skill to either remove a section of broken cast-iron and rebuild the radiator
OR you want someone with the skill to remove a section of cast-iron, drill and braze it. Either job can take some hours. The person with this skill has learned it at his expense and has gathered several thousand dollars of tools to do it. He had to open a business front and buy a truck to transport this equipment to and from your home. You would like this person to repair something that is no longer in production and is technically an antique. You would like this done for somewhere between $200 to $1000. Is this summary of your request correct?