In addition to the information on the forum, this article from more than 20 years ago, is a good place to start: https://sunbeamalpine.org/wp-content/uploads/2010/08/Vizard-Mod.pdfmxp01 and sunny67,
Clicking on the search box at the top-right of any forum page and entering "Vizard modification" will return a list of about 100 relevant posts.