If most of your riding will be in a relatively flat area or if you are a very strong rider, a single-speed bike is about as fun as it gets. However, the only one good picture I found of a Privateer's rear-end shows vertical dropouts. I wouldn't mess with converting a bike like that. If you can find a whole bike with horizontal or forward facing dropouts AND a crankset that will allow you to remove chainrings (some less expensive but decent quality bikes have them riveted together), a single-speed conversion is pretty simple. I recently did it to a 1983 Takara Highlander MTB and the only things I had to buy were a spacer kit for the rear hub and single-speed cog. I'm not counting the tools, which will easily come to more than the parts you'll need. I would have eventually purchased those regardless of this project.