I mean the PCV system could be the source of oil inside the intake manifold. If your rings are blowing by a lot, you'll have a lot of pressure inside the crankcase, which the PCV system is trying to relieve. Was there smoke & oil coming out of the road draft tube?
I just can't picture "oil sucking up from the lifter galley into all 8 intake runners".

cm

If you can't fix it with a hammer and screwdriver, you need a bigger hammer.
1965 Chevy C10