How cool! I think I read somewhere that the orinigal orange goop may be helpful in the crud off. I have had some success with paint remover taking off the rust. I took my singer 201 down to the raw cast iron, sanded and sealed it with Rustoleum for rust and I’m currently working up the nerve to rewire it. I can’t wait to see how your machine turns out. It will be totally awesome if you can restore this beauty!