Intake manifold pulling oil

1 degree will subtend .015" per inch. Even a tenth of a degree could cause an issue, but reading angles is the wrong way to do it. Angles are incredibly hard to measure accurately and I wouldn't trust any method outside of a metrology lab.

You need to do the feeler gauge check described above. Engine precision is measured in .001" increments or smaller. It's not uncommon for aftermarket parts to be slightly off. There are multiple ways to check the interface of the intake and head. My favorite I've read about but never tried was to use small Lead shot between the head and intake. Torque it, then measure the crushed thickness. Small diameter Lead solder wire could probably also be used. Calipers or a micrometer will be necessary to check for the amount of taper.

If it's consistently leaking at the bottom of the ports and it's not bottoming on the China wall, then the heads or the intake are off. There's no doubt about it. If it wasn't, you wouldn't be sucking oil after so many different gaskets.