You can definitely make it shiny in between the pits, which is pretty easy IF you have another Shopsmith to provide the polishing power. But those tubes will still be pitted, and you don’t want to reduce the OD enough to completely remove them. So I’d go with your instincts to make this one a “user”. Then when you find a nicer machine, you’ll have the perfect tool to help do a showroom restoration, if you’re so inclined.
Here’s a link to my own adventures in 10ER tube polishing:
https://forum.shopsmith.com/viewtopic.php?p=270329#p270329
I don’t think I mentioned it in that thread, but to me the most important step after cleaning the tubes is to apply a good coat of Penetrol. That stuff wicks down into the pits, and seals the pores so that they will never again oxidize. When it dries, clean off the surface with mineral spirits, and topcoat with JPW (Johnson’s original paste wax). Good to go for another 70 years.
