If you have access to MS Word 2007 or later on Windows, there are a couple of very useful addins you should have a look at :
Toxaris' ePub Tools, it was specifically created for the issue you're dealing with, see ==>>
Index of Useful Links for Book Creators
TransTools (not free) addin, it has some overlap with Toxaris' addin, but it also has some unique tools for fixing scanned texts - such as its Unbreaker tool, see ==>>
Translator Tools.
I use both.
BR