First, I've not heard of the crankcase pressure being higher on one side of the engine than the other, and it doesn't sound right to me. Second, I looked at a few old threads re "catch can" and didn't see anything about crankcase pressure. So I'd like to see a link to the discussion that does. Third, I did find a discussion that suggested that the right side valve cover would have a higher
oil level (and thus more
oil droplets in the vapor) in race cars driven by high level drivers on a counter-clockwise course. That is because the G forces would pull
oil toward the outside during the mostly left hand turns. As the OP is not likely to fall into this category of user, I stand by my earlier opinion that it doesn't much matter which valve covers has the PCV connection and which has the breather.