We had a Vulcan Storm Cleaner at college. It got stuff so clean that the stuff we cleaned would flash rust if we didn't spray the stuff down with WD-40. One of those would take care of that surface rust. You'd still need to clean out the oil passages with a wire brush. Would take the rust off of those timing gears too. It would be worth it to me $$$
to get it all that clean to pay a shop to do it.
