Alllrighty...I should have a few prototypes by the first of the week.
The cost is pretty close to what I was hoping, so I should be able to sell them cheaper than what that other guy was selling his for (trying to keep it at or below $15) ...and no set screws.
It's going to have the proper broached hole, same shape as the stock slipper plates, bolt on -- bolt off.
I'll post some pictures as soon as I get them in my hands. If everything works out, I should have the production parts within a couple weeks.