Try to remove some the of OD material with emery cloth.. File a bevel on the starting edge... Through it in the freezer for an hour... Just before trying to install it Heat the head up with a heat gun then go for it...
Take out the driver side fender well that may help... I did mine while the fuel rail was off and laid across the top of the engine.. while tapping it into place.. I felt mine was not in very far but it has held up with 60+lbs of boost..
Also look at my photo bucket link, I took pictures of the install..