You might try electrolysis to remove the rust.
Buy a box of washing soda, you can use baking soda but it doesn't work as good. Get a plastic container big enough to completely submerge the skillet in. Mix some of the soda with water, you will need an electrode, a steel rod will work fine. Get a cheap battery charger, connect the positive lead to the skillet and the negative lead to the electrode. Make sure the two don't touch, plug the charger in, you should see bubbles coming off the skillet, leave it over night.
The next day remove the skillet from the water/soda solution, the skillet will have a black coating on it, take a pot scrubber and running water and clean the black off of it. The skillet will be shiny new.
Then just cure it like any other skillet.
Homemade Offset Reverse Flow Smoker.
Horizon 16" Classic
Burnt up Uniflame cheapy.