When I get kit, I don't have the tendency to start right away (tho it depend). I wonder, do you think the windows on the "chambre des volontaires" drawings are larger than what heller/tanneron did? If yes, how much larger? If I take the heller breadth, it's 1cm, wich would give 5mm for the half panel/window, the heller panel give 4, not sure it'd be worth it to enlarge for just a mm.
Edit: Forgot to ask what are the differences between part 122 and 123 because I don't see them, I classified them, but messed up putting the wrong cariages in my cup by not looking at wich one I was putting them in only seeing my mistake too late.