If it is running OK with the 42's, unless you have access to an air fuel meter then IMO leave it alone.
That said, you might want to lean-out the pilot screws by an eight to a quarter of a turn (turn them clockwise "in" to make leaner) at a time & retest each time; provided you don't get lean-surging at cruise or hesitation on acceleration, then fuel economy should improve. If you keep going until you encounter either lean-surging or hesitation, then you'll know where the lean limit is.
Keep in mind that the fuel mixture will automatically lean out in colder weather, all other things equal.
