Where can I find a list of CheckIDs for sp_Blitz?
Sure, it's in Markdown here: https://github.com/BrentOzarULTD/SQL-Server-First-Responder-Kit/blob/master/Documentation/sp_Blitz_Checks_by_Priority.md

If you find any inconsistencies with it, check out the Contributor Guide for how to open issues in the GitHub repo, discuss the changes you want to make, and check in changes.