The head gasket should not be a problem as any fault would result in either compression, coolant or oil leakages but not heavy smoke.
After replacement of the seals, how much running time have you covered? Could it be residual oil in exhaust shyatem? I would suggest monitoring the oil level after some running time, maybe 1000k and see if there are any oil consumption.
As I mentioned before, piston rings would smoke at high engine rpms and is not likely to smoke at start ups, which are normally from valve seals.
Sunday, February 6th, 2011 AT 6:00 PM