Cleaning rusted cast iron

I'm looking at some really rouch cast iron, mostly Griswold and I was wondering how best to clean off rust. I'm not concerned with any seasoning that might have endured, I just want to make sure that I don't damage the material.

Soak it in Coca Cola.  The mild amount of phosphoric acid in the Coke will dissolve the rust.  Then, just wash in a mild detergent so it doesn't dry sticky.

Once clean, I would re-season it with lard.  When cast iron cookware was in its hey-day, lard was the only readily available cooking oil, and the two materials seem to be made for each other.