I don't know how aggressive wintergreen oil is, but I would not do any strong rust removal treatment, certainly not electrolytic which is about as drastic a measure as I know of. short of sandpaper.
Oil and a coarse cloth or soft brush to get the active rust off and leave the patina of hard tight oxide is about all I would do to it.
The grips PetahW shows are for a New Model No 3 and will not fit a Schofield.
This is the style, but Schofield grips were walnut not hard rubber.
http://www.midwayusa.com/product/565...ProductFinding