We are busy overhauling the engine

We are busy overhauling the engine. We replaced the pistons, rings, valve stem seals and rebored the head. She started but was smoking badly and over fueling. We opened the engine again to find the wrong valve seals were put in so we replaced this again. Now when we start her she is still smoking and there is oil laying on top of the pistons. Please help as we do not know what is the coz of this?