If the engine can hold a seal for a good long time after bringing the piston up to TDC, that's a very good sign. After dousing / lubing, etc., the prop should "toggle" freely after flipping through compression. It's a good idea to rotate the engine and try to feel for anything that isn't velvet smooth going on.
Pulling the head and backplate is OK to be done routinely, but the piston / liner shouldn't be disturbed...there's nothing to be gained unless there is a known problem that needs to be remedied.