Hi,
I had a couple thoughts regarding the oil leak problem with the valve cover or manifold.
First I see that the chrome valve cover on gbauer's engine is the cheap import, but the cover in fingersix's photo shows a factory valve cover(see script?). I consider the import scrap. But the factory cover ought to seal assuming it's straight and a good gasket installed.
As to the exhaust leaking oil, I'm thinking you might want to pull the valve cover and make sure the oil return holes in the head are open. If oil builds up because it can't return to the pan fast enough it could leak down guide when engine is shut off. Take a look for cracks on valve guide bosses too.
The aftermarket manifolds some times don't play well together where they meet on the mounting surface. If one or both flanges are a hair too wide and they don't have clearance next to each other they may not fit flush to the head and as you tighten the bolts down one runner may bow out away from head.
In my case it made for a hard to find vacuum leak as the gap was at bottom of center intake port. I didn't find it till gas started leaking out and down block. ( yes it was hard to start with a big vacuum leak!)
Hope this helps. Let us all know what you find.
