200tdi cyclone breather hose

In order to make life a bit simpler for me this week, could one of you smarter folk please answer this :
Does the cyclone breather pipe absolutely need to link to the air intake, or can I let it vent to the atmosphere as I've seen others do? If it needs to be connected, does it make a big difference whether it's connected pre-filter or post-filter? I'd have thought post-filter would be better, but I've seen plenty that are connected pre-filter ( if that makes sense!? ).
Also, is the 19j air filter too small to provide adequate air for the 200 engine?
Reason I'm asking all this is because I want to rectify the slightly bodged job the last owner did during the 200tdi Disco conversion. Possibly by doing some more bodging!

Route to atmosphere no problems unless doing serious off roading deep water etc
99.999 percent of breather pipes will be fitted after the filter otherwise the oil mist will end up messing up the air filter.
Both my tdi engines are routed to atmosphere.
Not sure on the 19j filter housing, but in mind simple mind they are both 2.5 litre turbo diesels so its got to be okay as a starting point if nothing else.

Cheers for that lynall! Reason I ask about the 19j air box and filter is because it's a good few inches shorter than the 200tdi one and will therefore make fitting less awkward. I don't want to compromise 'performance' too much though!