Mark,
Go back 4 or 5 posts and look at the "thread size" post.
Find the link to the Stainlessbits list . download it, print it off and keep a copy in the workshop.
Nearly every BSA / Triumph nut & bolt. thread type, diameter, length (sometimes finish) and use.
Just remember that BSA used the same bolts for hundreds of different places so don't worry if your tool box bolts are listed as handle bar bolts because that was where they were used first