Nightrider,
I take it you are one of the lot doing this.
The issue is very controversial for Moroccan Pilots thus comes the complications from the Moroccan DAC.
A conversion course is required by all Aviation Authorities from Classics to NG and vice versa.
The hours obtained on the NG should be enough for anyone to go back to Europe and get a paying job, and too often most JAA rated guys have both 737 endorsment on their licenses.
So the offer remains valid for Atlas Blue provided a "classics" endorsment existed on your license before joining for line training.
This begs the question: why would anyone want to go back to classics if they can fly on an NG?