top end breather hose

I'm new to motorcycles and have no mechanical expertise. That being said, my Dad (motorcycle genius) and I are restoring a 1981 KZ650, my dad has tasked me with finding a solution to the top end breather hose. We removed the air box and put individual filters on the carbs, which leaves two openings which entered the air box (the crankcase and breather hose coming from he front of the engine. My dad believes we can place an air filter over the crankcase but doesn't know what to do with the hose other than constructing a catch can. Anybody have any advice or run into similar issues while trying to make a cafe and opening the battery/air box section of the bike?

No eBay APP ID and/or Cert ID defined in Kunena configurationAt the valve cover most guys just connect a hose between the two ports. Another way is to cut threads & plug the ports. Or you could get some block off plates (see link). I've seen others that're kinda nifty looking but can't seem to find them. edit: KZ/GPz plates

A crankcase breather filter might allow water to enter the crankcase & I guess a filter could get clogged w oil & dirt. You could install a hose & route it behind the engine, but don't overfill the engine w oil, something you shouldn't do anyway.