I don't have any dimensions, but then again i didn't look for any when I made mine. Either I got lucky, or "close" is good enough because it works great.
You can see pics here:
I also have a few pics here that show the upgraded jig with the same fingernail fixture. I added a strip of metal to help register the flutes of my gouges, that's about it. Those pics are here:
One day, i'll get everything in the same place.