I am with Rich on this. Mine came out of a large truck engine. Not sure of the make or model but it shows absolutely no sign of wear so could be brand new. It is as accurate as any of my gear can test.
If your TPG wheel is trued from the side also, touch the end of the square (the ring part) with it to true the end. And unless your wheel is as thin as a cutoff disc there is no issue in doing so. On a cylindrical grinder that's the most efficient way to remove metal, as it acts like a horizontal Blanchard grinder.
Amount of experience is in direct proportion to the value of broken equipment.
Wrist pins are not as cheap as I thought they would be. I don't know what size the one in the picture is but I'm guessing it fairly large.
I have a 14" length of 3" diameter chrome plated column from an Instron tensile testing machine that was being shortened due to the ceiling in its new home being lower than its old home. Its diameter is constant to better than a tenth all the way along. Haven't got around to turning the end yet, but it's on the list of things to do.
There are fairly cheap CAT wrist pins on Ebay. Im sure searching for other makes would show more.
The wrist pins may be perfectly round and have exact dia's. to the tenth on each end but are the ends square ? I'm guessing not square enough to become a precision cylindrical square without some work. The ends of a wrist pin are really an insignificant surface since all they contact is the spring or circlip.
So I you happen to find one now your tasked with squaring up at least on end.