I'd probably throw the whole thing in an electrolysis/evapo rust/oxalic acid bath and then see what you have. The sole may not be as bad as you think, but the rest of it looks pretty rough. You never know though, clean it a little and then reassess.
The lateral adjustment lever appear to be missing, the lever is broken on the lever cap, the blade and chip breaker may or may not be salvageable.
It would take a lot of time (rust removal and making new knob/tote) and maybe money (frog, blade/chipbreaker, lever cap). After some cleaning, the only thing left worth salvage may be the body and maybe the depth adjustment knob. Buying new parts could get expensive, your best bet might be salvaging what you can and selling some parts.
It was free however, so I'd at least do some rust removal and see for sure before spending more time/money on it.
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