RS2K,
No offense but if your first post was worded correctly then you have left and right on an airplane mixed up. When you stated that the left side of the motor mount was forward of the right side were you facing the front of the plane perhaps? When you are facing the front, your left is the plane's right. Again, I'm not trying to be sarcastic, just trying to understand the condition that you actually have. At any rate, washers will be fine as mentioned.