I pondered this for quite a while. I know the OEM PCV system vented from the draft tube. I also know that others have retrofitted their engine with the PCV valve in the draft tube location. But, on the other hand, more "modern" engines like the 230/250/292 put both the PCV valve and the fresh air intake in the valve cover. Like Jerry said, it doesn't matter where the things are located, as long as there is a vacuum side and a fresh air side.

-Tim
'51 Chevy 3104 w/'56 235, 848 Head, HEI Dizzy, Corvette Cam, Split Manifold and Dual Carter YF's