One thing no one else has said is that down thrust is dependent on how the plane flies, not on how the cowl looks. You may be one of the lucky ones where the two match up really nicely, but it may happen that the flight characteristics dictate a different angle than the one that is perfect for looks. I'd suggest flying it with the cowl off the first time so you can test the down and side thrust and get it right, then you can finagle the cowl to work with the right engine position.