Categories as an “HTML Page” (Permalinks)

Hello everyone,

I’ve tried to search for this and can’t seem to come up with anything that I want.

I’m looking to change my categories to something such as this:

CategoryA -> http://www.thesite.com/categorya.shtml

I know that many people say it doesn’t matter if you have an actual “html” page vs. /categorya/ but in my case, it does. I have converted from a static shtml site and several of my pages are Google ranked 6 or higher and I’d like to keep them.

Is there anyway to do this in WP yet? Thanks so much!