Originally Posted by ThermionicScott

I figure it should be simple geometry. If you use the two contact points of the lever body as your reference, the distance to the hook of the brake lever will be some multiple of their spacing. For example, the contact points on this lever are about 1.25" apart. And the hook of the lever is 4.5" from the upper contact point, so it's a 3.6x multiple. So (forgive me for switching to whatever units are most convenient) if you were to sand 1mm off the bottom contact point, that should bring the hook of the lever in by 3.6mm:


Of course, imprecision happens in real life and my assumptions may not be completely valid, so it's always good to do a little at a time and check how it's turning out.