OK, it works; not following the mods as told on the tonepad site, because they will destroy the feeling. Just leave the 62k and the 100k as the bias and it works great.
My main problem were the IC's. I used ST 4069's and only when I replaced them with Philips versions, it came alive. I had some wah with the ST's, but with the Philips the wah got more pronounced.
The volume drop is now partly fixed, but I am satisfied. I replaced R2 with 100k, C4 with 0,01 µf.
Nice mod: replace R1 with a 5k pot (or in my case a trimpot); this make the whole effect more intense