As above, going from NPPL(M) to JAR PPL(A) is very difficult with very little allowances.
However, going from NPPL(M) to NPPL(A) and then NPPL(A) to JAR PPL(A) is a far easier route. You may still have to redo the written exams, but the flying allowance is much better and you'll only have to worry about the longer QXC, which you could include in the NPPL(A).
Admittadly it does involve more flight tests, but I've seen a few guys do it and it works well.