The reason the Fuzz sounds terrible with a buffer is because the source impedance is too low. The input impedance of a Fuzz depends greatly on signal level. A Germanium emitter junction has a forward voltage of only 0.2V but the guitar can easily produce voltage higher than that (if you really bang on it just so, it will make 4Vpp+). So the input transistor is being tortured on and off. When the 0.2V forward voltage is reached, the Fuzz input impedance is very low (just the emitter resistance). When the signal swings the other way, the transistor is hard off and the input impedance is at least 100K depending on the Fuzz pot position. A forward conducting transistor also rectifies the input causing the coupling cap to charge up. This causes blocking distortion.
The solution to this is to add series resistance. This is what the volume control does and simultaneously reduces the level so that the first transistor is not being tortured on / off.
Another problem with Fuzz is high frequency content. Most Fuzz sound pretty horrible IMO. The ones that sound good have transistors that do not have the bandwidth to make high frequencies (and they have to have the right bias and leakage and gain and other properties that are elusive to characterize). You need to high cut those high frequencies. Then even the blocking distortion can sound good (like Spirit in the Sky which is a Fuzz builtin to a tele).
So looking at your circuit, I would just replace the coil with a 10K resistor. Then change C2 to be more like 4n or whatever value you need to high cut at about 4kHz. Experiment with different R and C to cut off around 4kHz. Try 82K / 470p. Etc. However, this will mess up the 470p on the output. You can drop the 10R1 (which is nothing compared to the series R) and adjust the 470p on the output to give you additional high frequency control when rolling off the volume. If done right, you'll have a two pole filter when the volume is rolled off.
However, you really need to filter the high frequencies on the output of the Fuzz. This is actually more important than what you're circuit is doing. Everything above 4kHz from the Fuzz is just nasty annoying garbage and needs to go. The best way to do this is to run it through and old Alnico speaker. If you run a fuzz into a power amp (not a guitar amp, a hi-fi amp) driving an old speaker, it will brick-wall filter the high frequencies and make the Fuzz sound way better. A speaker like a Jensen P12Q is perfect. It will completely crush everything above 4kHz. Obviously you can't do this in your pedal chain. But if you have a high cut pedal, that might work too.
When I do a fuzz, I just go from the guitar > Fuzz > buffer and then split the signal to reverb and then send both dry and wet to a hi-fi amp driving two old P12Q speakers. Put the dry in your face and reverb on the other side of the room.
