Conversion to FAA licenses is not as hard as the other way around. If you want a FAA PPL you will be able to get one with no hassle just by filling in some paperwork. If you want a CPL you will need to complete the straightforward written exam and do a skills test in a complex aircraft. This may take a few hours to get used to american procedures and manoeuvres such as chandelles, lazy eights and eights on pylons are all covered as well as the usual stalls, nav etc.