The problem with doing it as suggested above (both rockers into the catch tank, then a natural vent to atmosphere from the top) is that gasses do not circulate around the engine.
If you have a search around v8forum.co.uk you'll see they advise to keep a flow going round.... that's why on the standard efi v8 there is a mushroom on the top of one of the rocker covers and the other rocker goes back into the suction in the plenum / inlet. on the carb'd models there is a pipe from each rocker back into the plenum but then they also had a breather at the back of the engine in the valley.
I've heard of people running small vacume pumps on catch tanks to get it to circulate and then having an "inlet" somewhere on the engine.
It was also suggested above that you put "splash" guards below the ports on your rocker covers. If you use the older style rocker covers (carb'd ones, stage 1's etc), it's easy to get a pipe on and those engines came with little splash plates that bolt onto the rocker bolts for this very purpose. Again, it depends on if your rockers allow this if they're different ???? (I may have a spare pair knocking about).
Don't forget to put flame traps in line
HTH
G