I’ve found that polishing steel is kind of like polishing platinum. It’s not as easy to polish as silver or gold. Because of that it’s probably best to start with gentle solutions, see what happens and go from there. Like I said before, you don’t want to add in deep scratches that you have go spend a lot of effort to remove.
As far as I know Simichrome is to maintain steel that’s already been polished and just needs a touch up. My experience with Simichrome is that it’s a chemical polishing cream and a very mild polishing abrasive. (I don’t know what the chemicals are?) You apply it with soft cloth, not a buffing machine. Give it a try as a first step. It’s not going to hurt anything and if it works, it will save you a lot of work.
But if you have dents or deep rust spots those are going to have to be removed with a file or sander and then polished.
What I like about bobbing compound is that it’s one of the most abrasive buffing compounds and has a fairly greasy binder that doesn’t promote buffing compound caking on what you’re buffing.
Another path is to consider some of the info in this thread. But again if you have dents and divets those will have to be removed with files or sanding followed by buffing.
Unrelated, I reached out to Steve Frei, owner of Otto Frei yesterday to see if he was interested in buying the whole lot of your stakes and hammers. Steve said that he’s not buying used tools anymore, but we talked about stakes in general. He said that Grobet is making some stakes that are special order, but they’re $1000 each. He said that Fretz has some medium size stakes for $300ish. He said that he was working with blacksmith who was making stakes, but that he’s gone out of business. Steve said the used stake market is pretty much what’s left right now. Kind of sad really. But maybe good for your friend that you’re helping!
One other thing to consider is since you’re selling them, do a minimal amount of refurbishing and let the new owner take it on. What you’re proposing to do is very big job!
Jeff