I have an ongoing quest to improve the effectiveness of my front brake.  Looking at it last night, something glaringly obvious struck me – the shoe cam plates are not centred around the cam, with the trailing shoe being moved by the toe of the cam, the leading by the cam flank.  This leads to differential lift and therefore one shoe doing the work, the other just dragging.  The contact faces of both linings agree with this.  Measuring at shoe contact, I have 2.6mm lift on the leading shoe, 3.8 on the trailing.  The cam is 30mm in length.

Is this normal? Or do I have the wrong cam?

What dimension should the cam be?

If it is, has anyone modified this setup effectively?

Shortening the cam to 20mm would ensure both shoes lifted evenly, but I have a lot of lever travel with the current setup, so am a bit worried about increasing this by taking this direction.  Any advice gratefully received.