If you wish to convert to a JAR licence, no matter how many hours you have got, you will have to sit the JAR ATPL ground exams. If you meet the required hours for an ATPL (1500 TT, 500 multi-crew) then you just need to sit the JAR ATPL skill test. If you don't meet the hours and would like to convert to a JAA CPL/IR, you will need to sit the CPL skill test, but there are no minimum number of hours training that you have to do. Then you will have to do an approved IR course (in your case 50 hours) and sit the test.
Hope that helps.