To me, if you have 2 oil soaked plugs after 15 minutes of run time, then oil is getting into those cylinders. It either comes from the top or bottom. If you think bottom end is good, head gasket is good, valve seals are good, then I would pull that intake and take a look.
I believe it is the intake. I noticed some antifreeze seeping through the top of the manifold gasket right where cyl-8 is which is one of the soaked spark plugs.