Creation of a clean and stable MS Word document

I need an original manuscript in MS Word to be made accurate to the final print file that was produced. It is 65k words, circa 300 pages. Some edits were made in design phase, and I now need the original manuscript to match the final design file before commencing on a second edition. I suspect that the two documents will need to be read side-by-side to ensure that any discrepancies are identified.

I have tried various ways of exporting the design file to word. But, the level of formatting, etc. makes the exported file unstable in Word.