Based on all the threads I have read over the years, Roush has had a lot of valve stem seal issues. No intake issue stuck in my mind, but my memory is failing. I think I would do the valve stem seals first.
Often valve seal will belch blue when you first start the engine after it sits a day or two, as the
oil will run down the valve stem.
Oil will run away from the intake gasket. That may help diagnose it. You can prove a valve stem leak, but I'm not so sure a lack of a puff proves anything.
If you could attach a gun cleaning cable with a clean cotton swab to the scope and run it a bit into the head, wiggle it around, and pull it out, then see if there is
oil on the swab. If it is dry carbon the gasket is good, assuming you rubbed it around enough. If there is oil the gasket likely leaks. However if there is a lot of cam overlap, reversion flow might blow oil back toward the manifold, from a valve stem seal.
Its a bit hard to prove what it is by inspection, without turning bolts. It's a much surer thing to just change the seals and see it that fixes it. If not pull the intake and inspect very well to see if it was leaking.