I finally ask a local locksmith to order these particular pins (
https://www.internationalkeysupply.com/products/asp-a-26-101-porsche-911-928-keying-kit).
He charged me $130 in total (He bought the pins and keep them. I send him the lock cylinder and pick up after rekeying). Not cheap but I've no choice.
But rekeying causes other problems which are a bit annoying... I'll post another thread to list all tips and lessons learned.