Have a question about how to possibly restore this
 

I am restoring/ cleaning up an early 1900s Davis made Minnesota. It has been extremely neglected, looks like it was left in the elements for a long time. When I removed the backplate I didn't pay a lot of attention to it, until the other day when I was moving things around and I noticed that it has some of the black paint, some of the decals are still there but there's a lot of rust on it and even on the places where the black paint is missing in the middle of the decals. My thing is I want to keep it as original as possible, but I don't want it to deteriorate any further. Any suggestions for removing the rust without destroying the decals and black paint or how to preserve what is left of the decals and paint? The only thing I have done so far is clean it a little bit with SMO.

Thanks in advance for your help.

I know it isn’t a FW but there might be some useful information on https://singer-featherweight.com/blogs/schoolhouse website, they have lots of maintenance videos.