Show a pic of the valve cover.. I want to see if they have a lip on them..
I had a issue with the covers leaking.. it was due to the joint at the
intake and heads.. if you notice you have very little difference between
the intake and head... I had to clearance that area so the covers could
set lower.. it was very little to make them clear and the oil ran back to
the corner so I thought that was the leak.. I had to clearance the area
all alone the intake.. if you have alum covers they could be touching
the intake and not setting down all the way
EDIT
looking at your covers you do have a lip.. I think that lip isnt letting the
cover to set all the way down at the intake
I ended up milling that lip off.. all the way around.. mine was on a set of
W-9 covers