It is probably valve guides, with 200k miles they along with the seals are worn, espeacially the seals. The uphill situation may be allowing the oil in the top of the head to pool toward the back set of valves at a level that is over the top of the valve guide thus allowing oil to flow down the valve stem into the combustion chamber.

Another test is on start-up first thing after the vehicle has been setting for some time. At start up you may get a small quanity of smoke for a brief instant.

Hope this helps,