End of my little story!
I could have taken the patinated one, as it is, for 1.5K EUR. But when I asked the seller, if I could let it have be checked by my watchmaker before buying, he refused to, without explaining why.....
So I let it go, because the risk, to have to find parts that are near impossible to find, is to high for me.
......and the most important thing, the decision feels right to me....no regrets.
Thanks @all for your kind help
_phranz