Hey Cees! Great to see another B-25 built! Although, see..... Photobucket doesn't show the photos here at work, I could only glance at the thumbnails.
In any case, the dorsal turret was removed from the aircraft fairly quickly after the end of hostilities with the Japanese so if you want to build a B-25 with the turret, you are probably stuck with an overall OD over NG airframe with the Dutch flags only under the wings and on the fuselage.
You have the Dutch Profiles published by Luuk Boerman?