After looking at the pictures of the 1/1 scale Beurlys, I discovered that the big hole had the wrong shape.
It's not easily visible on the pictures, but the hole has been widened on both sides by 4 mm.
I made the central "plate" in front of the windscreen from a aluminium bracket that came from an old computer, and cut it wit the Dremel :
It's not finished, the curve side that rests against the windshield needs some work :
