Tried to hit you and cracked my monitor.   But seriously that is an interesting Fuzz Face type circuit.  I haven't seen that one before.  I like the gain control and the tone knob at the end is cool.   Let us know how this sounds.  If I have time I may bread board this one.  Thanks for the schem.

Yes you're right an LED/LDR is so much easier to make an actuator to block and unblock light then it is to roll a pot back and forth.  I made a Vox 847 too.  It sounds great.  I used a Radio Shack audio transformer for the inductor. (Info I got from the GEO website.)  But I need some way to roll a pot with this one and haven't come up with anything yet.

You can get the parts at Radio Shack if you have one near you.  I bought a variety pack of LDR's and a variety pack of LED's.  I used the yellow LED's although red would work too.  The LED stays on all the time so you'll need to find a resisitor size that will make the LED shine nice and bright.  The shrink tube around the LED is to focus the LED light to one spot on the LDR about 3/4" away is good.  With the heel down or relaxed state the LED should be blocked.  When you press down (toe down) the light should be un-blocked to let the light hit the LDR.

I'll have to try and get some more pics soon.  You can find a sound sample of the Colorsound Wah on my website.  I'm still working on it but check out sound samples of other pedals I've built.  I used a Blues Breaker I built as the distortion for the clip.
http://randallbarnett.homestead.com/SoundSamples.html

I put a diagram below that shows a flat lever in between the LED and LDR which blocks the light getting to the LDR.  When you step on the pedal the lever moves out unblocking the light from the LED gradually causing the wah effect.
If you look in the circle in the picture the black bar in the center is the lever.  The LDR is the white thing on the right and the LED is covered in black shrink tube on the left.
http://www.logmonster.com/images/full/?pic=Sewingped_1162536480-422-14165.jpg

I used this Colorsound Wah schematic below and put the LED/LDR where the 100k pot is going to ground.  I also replaced the 33k resistor going to ground with a 50k pot for Q adjustment.  The pic isn't that great but it might give you an idea of the setup.  I'm going to work on some better pics of the LED/LDR mechanism.  It works great too.
http://www.logmonster.com/images/full/?pic=cswah_1162439148-422-14160.jpg
http://www.logmonster.com/images/full/?pic=DS0010ns_1162432918-422-14161.jpg

I used a LED/LDR instead of a pot.  There's a lever inside that blocks or unblocks light as you step on it.  It works great too.
http://www.logmonster.com/images/full/?pic=d007d_1160300734-422-13888.jpg