I wonder how much dis-assembly you will HAVE to do? I've painted them up with kerosene before and helped it a lot right quick. I'm pretty chicken when it comes to total dis-assembly... My BIL uses diesel since it is cheaper. Turn it upside down and paint the inside like crazy. Then turn it another direction and paint some more. See how much good you can do that way. The Triflow oil does wonders.... don't know about solid rust - vinegar can clean up rust and so can muriatic but it will also CAUSE rust and eat paint. We have a blacksmith friend who restores a lot of old tools and that is what he says he uses. I'd say you want to get some oil on it after that.
I have a Franklin still in my car. It turns - lots of grime and cobwebs... bare dangling wires... rust.... dangling light... I wonder if the top could come off the cabinet and go right on a treadle base? This one might have to wait for spring when I can work outdoors. I'm going to have spring fever early this year - in fact I'm already showing symptoms..........