While creating a local catalog how can I restrict stockable items (i.e. only show non-stock items),

I am creating a Content Zone for a local catalog using iProcurement Catalog Administrator responsibility. As requisitions for stockable items get created through Inventory Replenishment process, I have a requirement to show only non-stock items as part of internal catalog on iProcurement. Restricting purchasing category is not an option here because purchasing categories are shared between Stock and Non-Stock Items. Can you please let me know how to achieve this with current available functionality for internal catalogs in R12.1.3?

Example:

Item A, Purchasing Category=XYZ (Stock)

Item B, Purchasing Category=XYZ (Non-Stock)

Purchasing Category (XYZ) mapped to Shopping Category (XXX)