I recently purchased a job lot of NOS and used Alfa Romeo parts. After culling the junk (like 12 m^3) and sorting, I have made an inventory of parts for sale. Not by any means a comprehensive inventory, but that part you have been looking for may be there.
For lists, go to my web site:
https://www.qvae.com.au/for-sale (https://www.qvae.com.au/for-sale)