New motor blowing oil on headers

Don't worry about the PCV right now. I think you'll have to drill and tap a pipe thead port into the manifold to hook up the PCV valve. Or check the back side of the carb base plate, there might already be a hole there that is plugged. Never seen a Holley 950 XP up close, so I'm just guessing. A big oil leak like you have is quite obviously a mis-installed gasket, seal, or mechanical problem. Why not clean everything up and run it again? You ought to be able to see it leaking a little at idle if it's as bad as it sounds.