I read a long time ago somewhere on a guitar forum that a test to do to check the quality of the couple body / neck was to see if the body would hold to the neck without any screw.
Test result: it holds as you can see in the picture below.
After discussion with Patrick we agreed it would be a shame to use a completely opaque paint on the body because it would hide the beautiful Ash wood grain. We therefore opted for a white Mary Kaye style, ie translucent kind of white
Next step: preparing the body and the neck.