Seems to already be that way?Serong definitely needs to nail those set shots but Brayshaw's play style/role in the midfield should give him more opportunities in front of goal.
If only one midfielder is kicking goals for us regularly it could be as much game style of the overall team, not just the personnel.
For me I think Erasmus and Johnson can kick goals every other game if they develop into the players we hope they do. Wingers contributing to scoreboard would help a lot too.