If you want to, do help, it's a tiny project of mine, very... creatively... called "Comrades Library" and I'm just trying to create EPUBs of stuff, so there will always be something on the backlog. Maos Five Essays is currently the only one my list.
In this case I used OCRMyPDF to get text out of the PDF (Calibre doesn't do that), and then I'll create an empty EPUB in Calibre and import the text slowly, going through it with the PDF open to ensure it is correct, then finally add tags.
Tell me more about breaking bedrock, it might just be some setting I need to change.