Sorry, I meant to say .mobi in the title, not .ePub.
I see what you mean about the regular/tagged .pdfs and unfortunately all I have is a regular .pdf (no source document).
I tried putting the pdf I got out of BRISS on the kindle and it looks better than I had expected. I need to run it again to make sure every page is cropped to the same size, but it seems workable otherwise.
Thanks for your help