There's a Conversion Input PI for DOC ==>>
https://www.mobileread.com/forums/sho...d.php?t=229166
Haven't used it, apparently it does the conversion to DOCX using the MS converter
I convert a lot of DOCX to ePUB, my experience is that its better than Filtered HTML or RTF. I converted about 13,000 DOCs to DOCX shortly after Kovid released the DOCX input feature - he's done a lot of improvements since. The documents I convert are simple.
BR