I'm not familiar with the big Continentals but the induction system (carb, air box, and intake manifold) is completely different from the breather, which is a crankcase vent. Some oil out of the breather is not uncommon, especially if there's no oil separator and/or the crankcase is full. On my Lycoming, even though it holds 8 quarts anything over 5 goes right out the breather.