As HarryT says, if text flows along side an image in an ePub then it should in KF8. Note that the Kindle Previewer (get it from the
Kindle Format 8 page) includes KindleGen, so all you need to do is import an ePub into the Previewer to get a KF8 mobi.
There is a fixed layout option in KF8, but this is different from everyone else's fixed layout approach (
Fixed Layout in KF8 for Amazon Kindle is Disappointing). In any case, with fixed layout you would need a widescreen version (Kindle Fire) and a 4:3 version (iPad, Kindle Touch).