Graham,
To me the starboard cowl seems to be misformed. Near the firewall the cowl should be on top of the edge of the cowl on top of the tank and ammunition boxes. I do see the small edge on this cowl, but I don't see a matching top motor cowl. Perhaps somebody else had the answer for the OAW version, but the cowls on my Fokker D.VII are shaped differently. Perhaps you could have a look on the WNW website. They have pictures of all the sprues in the kit, which you can enlarge and make a comparison with your parts.
regards,
Ivo