Thanks for the advice. As far as I can see, no attempt has been made to restore the bike. No clue what really happened, as the structural damage looks like a crash happened but paint has no scratches. It seems from feedback that repairs will likely be both costly and damaging to the unique paintwork (which indeed is not made anymore due to some toxic stuff?). Costly is not the main problem, but damaging the finish will be.
Well, i bought it for the fork and I have another Montello in Spumoni colors with a broken fork, so I will probably stick to my original plan to use it there. Better one complete Montello on the road than two broken ones hidden in the shed...
Too bad, as this is the most beautiful finish I have seen. I might use the frame in some creative way (without doing further damage in case I will give it another try in some years).
Best,
Kees