Try denatured alcohol on the silver paint. I can't imagine that it was rusty....I have seem old Singers that were stored in a barn and never saw a speck of rust.
If you can get the paint off....and a new belt and get the moving parts oiled....and new needles and bobbins....you should be able to sew just fine with it. No electric motor to mess with!
Linda C

Never seen rust on an old treadle either. Sometimes a little on the iron of the treadle works. Did you mean 1887? Depending on the date of manufacture, appropriate needles can be hard to get, but there are online sources who carry original ones if you can get a size on them. The bobbin should be with the machine, or several in fact. If it's a round bobbin you may have better luck replacing them. My machines are all long bobbins but they're available as well online and are old salvadge originals. The bobbin chase is another story, so hopefully all parts are intact. It's also hard to get good leather replacement belts. I buy belts from Lehman's hardware in Amish country, but they carry rubber ones and they are not nearly as good as leather. I have no clue on how to remove silver spray paint. I successfully removed gilt paint somebody used on a pair of 1930s lamps with acetone nail polish remover, but I guess it's going to depend on the solvent carrier in the paint on your machine. What a pity. By all means, try to get that serial number. It'll nail your manufacture date on an old Singer.

I bet the date is 1887.