Guys, if you ever get truly high-centered for a specific bolt, you might try calling my sister Michelle at Patterson Hardware: 805/524-0476.
She's now running the family hardware store, which first opened in 1919. Pop took it over when Grandpa died in 1958, and increased/filled-in bolt stocks until he finally passed a couple years ago. Last I visited, they were carrying bolts from #1X 1/8" to 1" X 12", in both NC and NF threads, and in several heads and finishes.
They also have a pretty complete stock of soft-iron rivets, should that little issue ever arise for you, and she does take (debit and credit card) orders by phone.
And yes: as you can imagine, doing a complete, actual-count inventory has been a nightmare experience, as long as I can remember.