I believe the draft tube has a couple of small diameter tubes inside, with holes drilled in them. We used two pieces of exhaust pipe about a foot tall welded to the driver's side valve cover on the race engines, with pleated cloth breathers about 3" in diameter attached to the tops with hose clamps. They still got saturated with oil during a race, so I cut a series of diagonal slots at a 45 degree angle in both breather pipes and welded in several downward-facing sheet metal baffles to deflect the oil while letting the crankcase vapors pass. No PCV on a race engine, obviously!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!