So I picked this setup up for $20. Wasn't sure where to place this but, if I install them, is the only way to add oil through the dipstick? Could I add oil through the breather?

 

Yes, but depending on how they've been installed on the valve covers, it may be a slow process to pour oil through them.

 

Gold anodized Moroso covers with Offy breathers...classic stuff!

 

Where do you plan to put your PCV valve? If you add a hole for the PCV, then you can also use that hole for the oil fill.
Ideally though, you want your PVC valve in one valve cover and the breather in the opposite one for proper engine venting.

 

Ok thanks. I'll just drill a hole for the pcv valve. Might do it on the side where I can get a funnel in.

 

Drill carefully. If the bit grabs the sheet metal, then it will mess up those nice valve covers. And use the proper PCV grommet.

 

A step up bit might work best here. Used them many times on sheet metal race car bodies with no problems. But as NoEmissions said proceed with caution. These should be steel and may drill slightly harder then the aluminum sheet I’m referring to.

 

Better be sure to install a baffle under that PVC hole too !!!