Sorry, I don't have a picture, but if you go to
http://www.mcmaster.com/
and search for "reamer" you'll see the various tapered varieties. Pin reamers are for tapered locating pins, the narrowest taper. Regular taper reamers, used for enlarging holes in sheet metal, work too, but the taper is a little steeper and the finish on the flutes isn't as good since they're not really intended to ream a smooth wall in a deep hole. I reckon almost any taper will work, but I like a narrow taper since my main fear with a tapered mount is that the stem will fall out.
My reamers I got from a machinist friend who got a BandAid box full of them at a flea market. I had to cut them down to get a large enough diameter.
Jack