273 intake manifold, and valve cover questions

Question: Engine ventilation moves in one direction correct? In through the driver-side valve cover through the crankcase and out the passenger-side pcv to the intake? What happens if you have the pcv on the opposite side?
I don't see any difference. As long as you have them on opposite sides of the engine it shouldn't matter.
Interesting enough, a slant/6 has them on opposite ends of the same valve cover.