Sorry I can not suggest a
Simple solution. I gave up almost at the beginning (2010) of using conversion
adjustments as a way of making it My Way.
I simply use the Editor and reverse engineer the CSS.
Or in some horrid cases that have inline styling

, try an Move that OUT to a CSS.
If you post the PG book ID (title), I can look at the way it was coded.
I did assume you got an EPUB version from PG, rather than convert from something else.