Understanding valve seals

Does it start to smoke just at idle after a few minutes? Smokes after you let off from WOT?
Were the heads ported? Cast Iron Rings?
As Above I would check PVC
I would check Intake Gasket , might be easier to pull the intake and look for oil in a port just for piece of mind.
Pull the valve cover and give a wiggle test to on each cylinder when the valve is closed , hopefully this helps