I dont think a Sunnen hone would get rid of his marks, they look too rough.
You would have to be a man of steel to hold that fork leg steady without it wobbling so bad the hone actually makes it worse. When I was a kid my best friends dad was a mechanic and had a beautiful Sunnen set-up, with all the hones, the rod sizer, even oil feed. I wrecked a fair number of lawn mower cylinders learning to use it, and it does not take long for your shoulders to start to burn
If the part is badly scored (like that) or even slightly out of round, the hone of course wants to follow what is already there. So you have to nut-up and hold it straight so the hone can true it. With a fork leg you would not have enough leverage to clean that I dont believe, and the walls being as thin as they are it might be tin foil by the time you did.
BTW, when John retired nobody wanted the business. Everything sat unused for years until the building was sold. They junked the Sunnen, a nice Monarch 10EE lathe, and the rest of the tools he left for the "next owner".
One thing I would try if you can find a small amount is Belzona. It looks like Hocus Pocus but the stuff is amazing and we still have huge pumps and large DC motors that do not fail using that stuff. Down side is the amount they want to sell you, I am not sure but I think the smallest amount they sell is something like 300 of those funny pounds things you guys buy stuff with.
Lee