So the machine marks on the stub of that input shaft have been bugging me ever since I received it. I talked with a representative of the company who actually made it and expressed my concerns, but he said it will be perfectly fine "as is". So I asked him if I could polish it up a bit, or would that negatively impact anything by doing so. He said it likely wouldn't have any impact either way, and if it would make me feel better, and I didn't get carried away with it, to go ahead.
So I did....
Chucked it up in my little lathe and then used increasingly finer grit polishing paper (from 1500 grit to 3000 grit) and then applied some Simi-Chrome.
BEFORE:
AFTER:
I wasn't inclined to take off too much metal to try to get all the machine marks out, just enough to make any riding surfaces of the shaft on the pilot bearing smooth and silky. As frictionless as practical. Shaft nub feels smooth as butter now.