so.. I got the bright idea to replace my valve covers with chrome valve covers. don't get me wrong, they look great. I just didn't put a breather in for the pcv. there wasn't one on when I took the old valve covers off. How would I go about putting one in? Is it needed? (pcv valve is in) if needed, do I need to take valve cover back off? (know I probably will) thanks ahead of time.

 

Yes you need a PVC to vent the crank fumes back into the engine. It also prevents blowby in the intake. The pvc should simply insert in the rubber grommet on the valve cover and connect to the hose that routes back into the intake.

 

the pcv is in. the filter inside the valve cover is not. there wasn't one in when I took the old valve cover off. do I need the breather..?

 

If you have a PVC valve installed in one of the valve covers it is important that you have a breather (or tube running to the air box) so that the crankcase can breathe.
I think what you may be asking about is do you need a "baffle" inside the valve cover where the breather or PVC valve is installed? While they are desirable they are not mandatory - I have had to delete them before when they interfered with aftermarket roller rockers.
OEM valve covers come with baffles to help prevent excess oil ingestion into the PVC system or oil venting from the breather. Most aftermarket valve covers do not have baffles in them.
I installed a pair of early Mustang 5.0 aluminum valve covers on my 91 5.8.
I had to swap sides with them and remove the factory oil filler and plate it over. I then drilled the valve cover for a trick flow filler / breather tube. The other valve cover was solid so I drilled it for a PVC valve and fabricated an aluminum baffle for inside the valve cover. (Sorry I don't have pics for inside the cover) The factory valve covers were so tall the PVC valve was remote mounted behind the intake plenum but the 5.0 covers were short enough to allow me to mount it in the cover - you can see part of it in the aft corner below.