If it turns over just fine with the ignition off but gives problems with ignition on I would suspect that the mechnical advance in the distributor is stuck. One way to help diagnose this is back the timing off and try to start. If the engine starts and sounds like it is loboring that is the problem.
Not a real bigie to fix just some time to disasemble the distributor and free & lube things up.
If I am guessing right what is happening is the fuel charge is igniting before TDC and trying to spin the engine backwards against the starter thus making it lobor extra hard and thusly smoke.