I can't find my 'don't mix metals' chart, but I always thought mild steel (cast iron) and threaded stainless shouldn't be mixed ?
Yes, although galvanic corrosion can take place between cast iron and stainless steel, the fact that the stainless part is so much smaller than the iron part and contact interface is so minimal, then in practice it is unlikely to cause a problem. (Note: I am not a metallurgist, just a googler!)
