The JAR are in force in Europe now, You can convert your licence in any country of the following:
danemark/UK/Islande/Netherland/Sweden/Belgium/Spain/Finlan/Irland and switzerland.
The licences provided by an other country will not allowed you to fly plane register in France.
Procedure:
You will need to seat for the written exams (12 with your experience). Flying part quiet easy with your total time.
France's exams are in French.
It will take you from 5 months to two years depending on your motivation.
Contact each civil aviation authority for details, some of the country mention above are not ready yet for the JAR exams.
Good Luck.