I tried to draw the layout, here it is.
My emulator says this circuit cut a bit the mid-bass frequency, so I suggest to try to replace 33nF cap with 47nF, 56nF or 68nF if you prefer a more flat response at half setting, though you will lose a bit of max bass cuttingat min setting of the bass pot.
You can try a log pot instead linear because it could be more effective just in the first half.
It's still UNVERIFIED, so as usually, tell me if you see something wrong.
(Is this the real schematic of the Fulltone Fat Boost 3? GGG called this schematic Fat Boostered.)
I build pedals