The reason that I asked was that the 3/8ths x 10 is my favorite pin.
It is generally a flat faced joint. I know some makers will use a Phenolic insert in the shaft
to make it stronger, rather than just wood threads. Good stuff.
Radial pins, same deal. Wood threads.
It seems that Ernie made a nice little adjustment to the way he uses that pin.
With many brass inserts, you see a tiny nub above the face of the shaft. If you look at the butt, you see a wide and deep void. So, that little brass bub doesn't do a ton of good and you can use a flat face in a butt that is made to accept a Pilot without any problems
at all.
Ernie's shaft pilot looked like it was designed to fit a little more snug both width and depth wise.
That is what one would consider to be a real Pilot. More on the functional side.
Still, the only thing the OP could do is try out a flat face shaft on the butt and see how it goes. No harm in trying. It will work just fine.