Interesting. I don't see much oil puddling, and it looks like quite adequate crush on the gasket, and I've had narrower rails that sealed just fine with cork gaskets.
But that area was the intake side. So, throwing some darts...
Have you measured the height of your hold-down bolts to make sure they're not holding the covers up a bit?
(Not that I see any witness of interference, but I'm wondering about heat expansion.)
I haven't experienced that problem with Eddy or Stealth or stock heads, but I have had a set of MP covers that barely provided enough sealing area.
The MPs seem tall enough not to interfere with roller rockers, but with stock covers & rollers I've had to fab spacers for the covers.