From my experience, the heads almost never go bad, unless the engine is really overheated badly. The problem to me sounds like the Valve seals, which is a pretty common problem on the 103 engines. Usually a job like that is about 3 hrs labor and maybe $100 in parts. Pull the spark plugs out and see if they are covered in oil. I would at least check them before I spent about $1,200 for a valve job, which may have not been needed.