Just make the holes in the cam covers and tee it into the existing breather system. Lots of vehicles use the cam cover as the vent system anyway.
They do, the ls1 has similar. However the ls1 is a pushrod design, so doesn't have two cams per bank spinning around inside splashing oil over the inside of the cam cover. If breathers are attached here, inlet vacuum will just hoover up oil from the engine and spit it out of the exhaust as smoke, and increasing oil consumption.
The location of the crank case breather box behind cylinder 5 is chosen as its a still atmosphere as far as oil splash goes.
There is a combination of air ways that lead to pre and post throttle to manage the pressure during closed and open throttle situations. These pin holes, about 1mm or so are obviously set sizes the factory made to choose vacuum levels and manage oil loss through oil vapour.
I have had a car where somebody felt the need to open up the oil hole on the breather box behind cylinder 5 by an extra 1mm or so. The oil consumption on that car was decreased by a litre a month by fitting a breather box with the standard size hole again.