Take the head off and get a valve job (or get a used head and have the valve job done first and then just do the swap). If the smoke goes away, this is your problem. If you burn oil at high rpm or use the manual trany to slow you down and then have smoke on take off, or smoke all the time... then you have worn rings.

The reason you only have smoke on start up is that the oil sits on top of the valves in the head over night, if there is a loose fit (worn valves or guides etc.) the oil leaks into the cylinder. When you start the car it burns up within a few minutes. Over time this will F-up your catalytic converter and foul plugs all the time.