Chevy 250 - Breather or Cap

[Mthumphrey]

OK guys. I currently have a stock 250 until I get the headers and intake installed. It has one of those air cleaner looking breathers on the stock valve cover and a PCV valve on the back side. I am getting a lot of blow back. I found that the PCV valve connector is all cracked and leaky which might explain a little oil leak I have been trying to fix. The question is... Once I fix the PCV valve connector, should I replace the air cleaner breather with a chrome breather or a cap? Cap or no cap is the question?

I searched a bit and have seen engines both ways. It would seem a cap would be best to close of the unit get a better vacuum in the system, but is there a reason a breather should be used in this instance?

Thanks!