I would use Creator, but can't see the option to convert ePub? Publisher edition v4.2 build 41.
Calibre is still too complicated for me. Few times I tried it, I did not like the result very much. Someday I'll be back asking for perfect settings, but not before I feel comfortable with html.
Presently my workflow (in more complicated tags) goes like this:
-copy the part I want to change in html (and sometimes paste it to another txt file)
-change in np++
-save in np++
-build in creator
-check what happened in mobireader
-if i don't like it, 'undo' or change differently.
I do not want to wait several seconds (with Calibre) just to choose pleasing color and size of the captions (for example). Also when I try something dubious, it's faster with Creator to make change in one or two places and only after checking change all the places.