Never use a JE for inventory in QB.
What you asked here: "They're not really inventory items insofar as they are never sold, but we do buy in bulk, hold them, and then distribute as they are needed."
Is "Adjust Inventory" and in that screen, top, you assign which Job it gets assigned to, for Relieving it from Stock on hand, but not actually Selling It. That way, you assigned that Cost to the Job and removed it from On Hand.
In the job reporting, you will need to remove the Account filter, because you do not want only ordinary income/expense; you want Job reporting to also include COGS.
You can see this in my attachment.