You might be able to save yourself a lot of time, money, and work by first trying a set of new valve guide seals. If the car sat for a long time, it's possible that the seals are shot. You can do this without pulling the heads too. Since compression test passed, you can assume that the rings are still sealing, so the only other logical path for
oil to get into the clyinder/exhaust is past the valve stem.
- Jim -
whoops... sorry, didn't see the PS before I started the above.....