Thank you all for your views.
My way is to clean & polish, and repair whenever possible, all original parts I can save, even if not perfect.
It's all the more true since repros are more or less poor.
So did I for the steering wheel motif, and I'm happy with the result.
Following Randall's and other's opinion I will try and have the grille motif restored too. But there is kind of a mystery to me about it: on photos (for instance in the knowledge data base) the crown around the growler appear to be all red
when on mine I can see, on the remaining paint, that only the depth (when looked at upside down) of the engraved rays are red, the rest being silver (as is the head of the growler).
I'd be happy to give the right instructions to the restorer if one of you knows about that.
Regards.