The biggest tonal influences to modern day wahs is changing to a better inductor and pot...I have an 847 Vox and I put both the Fulltone pot and inductor into my pedal,did true bypass,and added a 9v power supply to it..After that,it's tweaking some cap and resistor values to get a bit more fullness of tone,more range on the pedal,and a bit more gain out of the pedal.I'm currently doing just that to "Bludave's" old Crybaby wah...After that I feel the best sounding vintage sounding wah money can buy,is the Teese Picture Wah...It sounds alot better than Fulltone's wah..Teese is the guy who really knows wahs better than anyone else,plus he actually worked for Vox and was a repair guy for them..
John