Why not use PDFRead 1.8.2 located
here.
It converts directly from .pdf to .prc using a simple GUI! (GUI for Windows users only). It supports TOC, dilation of text, auto-cropping, edge enhancement, landscape/portrait modes, etc.
It is also possible to leave the converted images and .html behind after the conversion is done. Also a .opf is provided to allow further tweaks using Mobipocket Creator.
Give it a try.