I now live in the US and hold a JAR CPL(H), to get a FAA PPL(H) based on my UK licence I had to pay the CAA to allow them to verify my licence to the FAA. Then to get my FAA CPL(H) I had to take the CPL exam but first the school had to sign my log book to say that I had the knowledge to take the exam.
As for the flying test I had to just fly the required amount to reach the required standard for test.
Don't know if this helps.