Excess Crankcase Pressure

The hose to the PCV operates at hi-vacuum, so it needs to be PCV specific thick-wall stuff, or else it will get sucked flat at hiway speed, and then quit working.

The breather that goes to the air box must breath in both directions. If your engine is smoking, then the airbox should be full of oil, which is bad. If there is no oil in there, then the system is not working, and the pressure has to exit somewhere else. The dipstick is just the weakest link. and I have never seen an O-ring on it.
Your carb should have a nipple on the FRONT of it, facing the rad. The CC gasses should enter the throttle bores in close proximity to the idle discharge ports and transfer slots, so the blow-by can properly diffuse into the air-fuel stream. If you plumb it anywhere else you will have driveability issues, or plug problems. I would replace that #6 plug right away..

After you get it all plumbed correctly and working, don't be surprised if it still smokes for say 15/20 minutes, as the condensed oil inside the muffler, cooks outta there.