! Here's what I did.
Wire brushed loose rust, then naval jelly on all rusted areas. Laid plastic wrap over the jelly to keep it from drying out. Four hours later rinsed off the jelly, dried the chassis, then wire brush, steel wool, and rinsed to remove the residue. Bondo spot putty on the heavily pitted areas, sand the 6-0 wet sandpaper. Then mask and paint.
To get the original chrome-like shininess on the attached tube shields, I masked and painted with, what else?..., chrome paint.
That was a lot of work. It may be lacking in authenticity, but it looks pretty.
And now I have to put it back together again.