While reviewing an almost perfect Page to assign level 4 to it, I feel comfortable to compare wikisource text and image of the page in view mode; often there's nothing to fix, the unique change being to assing level 4 to it, or there are only minor issues. We are developing into itsource some scripts, to allow page code edit by ajax, opening an editing box in view mode; we added too some js to resize/drag the page image in view mode, to help reviewing.
The advantage is that the edit box opens very fastly, and itsource edit tools can be added to it for usual wikitext changes.
The whole thing is not addressed to first reviewing work, that needs the whole edit environment, but - as I told - just to retouch minor mistakes, and to give a look to the wikicode.
Alex brollo