I would suggest Universal Weather. I have used them for years and they have relationships with just about everyone. They also have peoples phone numbers and will call them directly if necessary. Something that many other handlers do not do.
Some of the big questions are, how are you planning to conduct the ferry flight? Will you re-register the aircraft before or after the flight? What nationality of certificates/licenses will the pilots have? Will you need to export and/or import the aircraft? The routing could be interesting with the normally short ranges of helicopters.
So you will also need a customs agents at both ends. Be aware that aircraft are considered controlled items so the customs paperwork and procedures may take a bit. If you re-register the aircraft prior to leaving the departure country, you will need proof that the aircraft was the previous registration and the departure country may have no record of it ever entering the country, which causes a lot of large red flags for officials and delays you. If you do de-register the aircraft you will need some sort of ferry permit. I'm not sure how JAA land does it. Plus insurance paperwork radio station licenses, etc.
It sounds like it could be an interesting adventure.