Raking the mast more aft will place the center of effort from the sail plan further back, putting more load on the rudders, making weather helm worse. Raking mast further forward should do the opposite. Raking the rudder blades forward will not change the forces on the blades, just how much mechanical leverage you need to apply to keep the boat going straight...think "power steering". In extreme cases, the loads can be so high on the blades that they ventilate regularly...a bad thing!

How is your jib setting when you feel the weather helm? Too lose? Remember, the main will tend to make the boat round to weather while the jib helps counter act this, bringing the nose off the wind. Perhaps you've got the main oversheeted for the course and conditions, while the jib is not doig it's fair share. What happens if you pay out the traveller a few inches while reaching? How are the centerboard & rudder surfaces? Are your rudders aligned correctly?

Mike