Valve Covers - To vent or not to Vent

[tsmith8]

I currently have a generic set of valve covers on my 327. They are vented into lines that terminate at the base of the firewall. (Not my setup, but just how it has been since i bought the truck)

I found another set of valve covers in my garage that i like better. They are not vented.


So the questions is:
A) Am i going to effect anything by having none vented valve covers?
B) just an FYI i have a vented oil fill tube.