Ever have oil get drawn in through the lifter valley?

I've been dealing with a detonation problem with my 440/493 and after all sorts of parts swapping, carb jetting, distributor tweaking....I think I may have found the cause: There is oil on the intake face. Oil on the valley pan at the intake ports. Oil on the heads around the intake ports. I found this today when I pulled the intake. Recently I replaced the '509 cam with a Lunati solid in an effort to stop the detonation.
During reassembly after the cam install, I decided to install the valley pan without the paper gaskets. I applied gaskacinch around the ports on both sides of the valley tin and set the intake. I have done this before and thought I had good results. THIS time, not so much.
I had detonation with the last cam and now I'm wondering if I had this same thing going on then. Has this happened to you?