My motor is smoking!

Make sure that the crankcase ventilation is working as it's suppose to, too much pressure will force oil by the rings as they become the weakest link for pressure to get by.
From the low pressure of the cylinders that you had before you may have washed the cylinders out with too much fuel and it will take time to get the rings to seat as they should. As low cylinder pressures generally dont burn all the fuel they generally get. The excess has to go somewhere and this excess will wash the oil from the cylinders and create a smoking problem when pressure returns. Use of a heavier weight oil will help this situation out quicker, and get it to either stop or slow down the smoking problems.

The heads have good guides and teflon seals, so the amount of oil that would get by them is very minimum.
Have you retightened the intake bolts after the engine was warmed up? You may find that the bolts are a bit loose, just as hedder bolts get loose after the warmup so do the intake bolts, as were talking about two different types of materials and expansion rates.
If all the things mentioned are in good shape then the bottom end is the fault.

As for the feeler guage, use the thinnest one you have, and the gap will be at the bottom of the intake where the manifold meets the heads. .004 - .005 wont leak with a gasket, even a steel gasket. As the ribs in the steel gasket are .020 tall and will take up the difference.