The full length valve cover uses a full length gasket. Don't worry about the bit of opening for the throttle rod. The later full lenth covers used the oval hole, prior to early '23 the hole was smaller round one as in this picture. There are plenty of spaces where dust will fly in and oil will fly out
Remember that there's not even a oil filter nor an air filter for the carb...!!
This picture is somewhat incorrect as the fasteners for the valve cover should be studs, with hex nuts,,,,shown are the later dome nickle plated valve cover bolts used in late '26 and into '27.