Definitely do an oil change after you're done. With cleaning the valves, is it possible for you to remove them? You need a special tool but once you have them off you can just wire wheel them. I don't know how well brake cleaner will get of the baked on stuff but if you do use brake cleaner in there it shouldn't be a problem as it evaporates off fully anyway. If you can't take the valves of you could try using a razor blade and scrape off all the flat parts on the valves and the whole head surface. Just be careful on the head so you don't slice into it accidentally.