ITBs

You only just sold me your last set!

Whys that? I run mine open, so much noises! 

Admittedly I won't be on the new engine I am building but on my current setup I dont have filters. 

No idea yet. Build starting in the next month though.

To keep as close to factory-style arrangement as possible you'd need an intake plenum and 2 separate catch tanks:
a) exhaust side PCV valve into catch can A; catch can A into vacuum block or one of the bodies after throttle;
b) intake side breather into catch can B; catch can B into plenum.
At part loads A provides vacuum, pulling fresh air through crankcase, the said air entering crankcase through B. At full load pressure / oil mist exits through B into intake and then combustion chambers.

Of course I can't imagine anyone doing it like this for practical (and performance) reasons. A reasonable solution would be to get rid of PCV valve and feed both valve cover breathers into a catch can with a breather filter. Or if you're lazy like me leave PCV in place unplumbed (PCV is closed as long as no vacuum is applied from outside)  and feed the intake side breather into a vented catch can. This is how mine is done.

Your mileage effect on environment may vary.

If you ITB it you can make this magic vacuum block. "omgpham" has a good guide on doing it against all cylinders on whatever his setup is.

...agreed with retroroadster.. defo toss the PCV valve with ITB. - if you do a vac block... Keep it pristine just for running the MAP sensor and brake booster. if you want to draft fumes out of the PCV side of the cam cover, get a nice 13mm-> 10/8mm reducer instead. or drill out the old PCV valve.

then VTA the breathers, via whatever you feel comfortable with. Many just toss filters on both sides and meh.

My overkill setup is described below:

My ITB car .. when I got it.. had a hot-side catch can with "burnt to solid" pipes and a cusco catch. and a draft tube - draft tube got me thinking - crafty japanese!, but it being hot-side and right next to the exaust the hose had turned to solid plastic. - there are two breather pipes out the cam cover.. so I thought... and bought a much nicer three-way catch (two inputs, one output) off mishimoto.

I still VTA but via said catch can which includes a particular filter (some small micron) and draft pipe on the output side. this is the lightest "not directly spraying it direct into the atmosphere" setup.

draft pipe is a hose down to the lower part of the engine bay, just past the undertray. OEMs don't do this anymore - illegal now.. - it used to be a direct vent on 50s/60s motors before the euro/california eco-law came in. with maybe an OWV to stop creature ingress, but still fairly eco-friendly if you put a catch can in between it and the breather pipes. just empty it now and then

when the car is moving, air passes the end of the draft pipe, causes a vacuum, which will pulls the fumes out of your crank shaft or cam covers - a bit better than just a filter would sticking out the end of the catch can, or even just a filter sticking on the breather pipe.

here is a shot of my setup. you can see two inputs into the little black catch can on the bottom left and one fat one going down to the undertray:

I ran no catch can, the PCV valve and a breather filter, no vacuum block; just one vac feed for the brake servo and four vac feeds T'd into one for the MAP sensor. I used Alpha-N mapping.

I ran that for three years, with no problems. I didn't even run filters on the ITBS. Actually, I ran a catch can for about 3 months, but the piece of prarrie canoe bracket it was on came off when I went over a pothole so the whole thing went in the bin.

I'm not saying it was perfect; my point is more that there's a lot harder parts of an ITB build than sorting your catch can setup out. Get up and running with ITBs and management first, that's the real hard part.