Go figure. Based upon these instructions from Codeholics, I started to convert MPR using the Python powered Pelican. Pelican did a good job of cleanly processing my WordPress export, and extracting my posts and other content. It looked like I was on my way.
Except my posts are written in Markdown and stored that way in the WordPress database. Which Pelican’s import function conveniently escapes when it generates Markdown. Sigh.
It may not be the most elegant way, but I think I can work around this with a custom fork of the Pelican source code. At worst, I’ll be flexing some atrophying Git muscles.