Blend control / morphing with quality

[Pablo1234]

I currently acquired an old Morley volume peddle and was thinking of using it to blend some effects together with it. One issue with the foot controller is that it uses a flap connected with a screw to cover an LDR and uses a light source(It is no longer their). I would personally prefer a potentiometer ganged with a gear like on the dunlops to controle one of my NSL-32's. Has anyone ever mechanically mounted a potentiometer to a foot controller like this? Any suggestions as to where to start for some prefab parts like a cam I could mount. Knurling the pots is not an issue for me, but I am not sure where to acquire a cam arm to match a knurl so to speak. And am I maybe wasting my time trying to do this and should just build a light fixture inside the box for the existing ldr and remake the board?

Basically I want to pan between 2 effect chains and have a clean mix pot off to the side but be able to pan between the 2 chains smoothly. Do I do a log for one and anti log for the other, 2 logs, 2 anti logs, or make them both linear. I haven't worked with panning effects before and I have a real use for this at the moment.