Oh I'm not at all questioning what Guisval labelled this car to be, which means it was correctly identified by Barrett.
I just think it's weird they should call it a 405, or even a 505 coupé as the real car's existence wasn't exactly public domain until recently (unless I am very much mistaken).
Which makes me wonder: how old is your model?
and what did they base the mould on? Guisval seems to be re-using old moulds of other manufacturers and maybe modify them, in this case I'd be curious to know what they started from.
But anyway, no fret over any of this, great puzzle I wish I'd come across sooner.
MM