I haven't used it yet but i believe it should work. Only difference is the bottom side isn't relieved. Used a step drill to 24mm into a piece of .250 aluminum. Cut the rest with a band saw. Maybe 15 minutes to get everything together.
(http://i1255.photobucket.com/albums/hh634/Huff1371/2012-06-05_16-24-03_713.jpg)
The viewing angle makes it hard to tell for sure....
The inner diameter of the "business end" of the tool should be constant and should match the diameter of the camshaft. The outer diameter should increase towards the back, so that when you seat the tool on the edge of the tappet and push the handle downwards, the tappet will be forced downwards - away from the camshaft - far enough that the shim can be pulled out through the space you just made.
If it's set up like that, you should be good to go. The "relief" built into the Motion Pro tool is handy because it helps you register the tool horizontally, but it's certainly not necessary.
Way to be a "maker"! :thumb:
Here is another pic. I scaled a pic that I believe was from you kerry.
(http://i1255.photobucket.com/albums/hh634/Huff1371/2012-06-05_16-23-52_694.jpg)