Intake Leaking Oil

The following is maybe going to sound mean.But its not meant to be.I dont know how to write in a gentle way.
You put the shims in all the wrong places. Of course you have the same measurements. How could it be any different?The way youve done it, proves nothing.You have forced the manifold to do whatever the heads are doing.
Think three legged stool. A three legged stool does not wobble.You need to set your intake down as a three legged stool.
You cant use a compressible shim, like paper.
You need to place the non-compressible shims in three places, as detailed earlier, so that the ends of one side are free to float.That means front and rear on one side and center on otherside.I would ransack the washer supply for three, fairly thick( in the neighbordood of .100), identical, FLAT washers;or equivalent.Put these shims; on,or very near to, the end bolts on the one side, and on or near to the center of the otherside.Torque the two-shim side down first, to around 12#.Then the remaining one to a lot less, maybe 5to8# Then measure the end-gaps on the one-shim side.
Then repeat the whole procedure,on the other side,swapping the shims side-for-side.
If your manifold is twisted, or the heads are running uphill/downhill, this will be proven by varying end-gap measurements.If everything is straight,true and not twisted, then that will also be proven; by equal measurements everywhere.