I tried the electrolysis method using a fence T post has my rod and the engine block as my piece to pull the rust from. I used a 12 volt deep cycle battery with a battery charger hooked to it set for 15 amps. It worked great.
if this worked well for you, try it with a carbon anode. any tool and die shop has this material is scraps. this is the material they use EDM machining. once they are done with its hazardous waste and they have to pay to get rid of it. they will be happy to give it to you, just tell them what you are going to use it for.
one question, does using a battery along with the charger give constant current or will it still pulse?