I’m confused (easily). Do you mean the hole in the rear of the block where road draft tube goes instead of intake manifold? If you’re talking about where the road draft goes in the block and you want to do away with the draft tube - I believe that hole should be used with your PVC system and not blocked off. How are you doing your PCV system?
The road draft tube in a W block is attached at the rear of the intake manifold,not the block.I agree that on N/A street engine that a pcv should be used as opposed to breathers,but that could change depending the level of your build.