I have no advice per the meerschaum pipes, but the briars would be fun to work on. When I get a pipe like that, I'll remove the old cake, and then take it to the sink with a spray bottle of Awesome! cleaner ($1.25 per bottle at DollarTree) and go to town. I'll use a toothbrush, a brass brush, wet-dry sandpaper, running water and lots of pipe cleaners, and the pipe will get scrubbed inside and out. Sometimes this approach will take off the finish and the color--sometimes not. The stem will get wet sanded with water and Awesome! cleaner. This is all a prelude to the sanding (maybe), re-coloring (maybe), waxing and buffing that would fill a different thread. Good find and good luck!