I use a piece of clean sheet metal as my anode, the more surface area the better it seems for me, after a day or so its covered with rust and my parts are clean, I actually got the siezed pistons out of a early hemi with this method, even after all the ol' time tricks, diesel fuel, mystery oil, coca cola, lighting the fuel on fire in the cylinders, air chisel, trying to drill out the piston centers virtually everything was tried but electolysis did it!
Your backing plates look good in the pictures, i use the rust removal process then lightly sand blast 'em too, the removal process makes the blasting process a breeze! Lookin good! Best of luck