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Ok so it's been some time but I finally got something together.
Ordered some beautiful germanium TO-5 can transistors and sorted out some low leakage (all below 100uA) ones with the following gains:
Q1: hfe 88, Q2: hfe 95, Q3: hfe 151, all measured with the Geofex method. (So this is "real" hfe)
Bias pots for Q2 and Q3 were set to 30K and 8K2, which sounded very nice to begin with.

So the circuit after the switch works nice and well, but when I switch on the Q1 stage, things do not work as they should. A lot more background noise and altough the signal itself is more distorted, there's less output.

Now there are two things to consider:
- Bias setting for Q2&Q3, which we already discussed. I haven't tried other settings yet, but maybe there are some that'll work better with the Q1 stage.
- I suspect that another reason for this behaviour is the pot before the switch. Even when it's set on 10, there's still a 250K resistance going to ground. (I used a 250KA for this try)

So my issue is that I don't fully understand this level pot circuit. It just regulates how much signal goes through and how much goes to ground, right? But doesn't signal going to ground cause noise to begin with?
Should I just try a higher value pot or even put an offset resistor between the pot and ground? (There's no use for the zero setting anyway)

Thoughts?

@midwayfair
First of all that's exactly what I meant by Fuzz Face circuit. Throughout the decades many versions using different transistors and cap/resistor values/types have been put on the market and even more people have adapted it for their own creations. I did not want this to come across as a reference to the original first Fuzz Face, not at all.
Thank you anyway on your input, dissertations like these are always greatly appreciated!
(And by the way this does not at all discourage me, this is food for my brains!)

On your input towards the bias compromise:
The result of course depends greatly on the choice of transistors. For example I've built my first Tonebender MKII "clone" with NPN Germaniums, since I didn't know about voltage inverters back then, later I added the mentioned switch and it works just fine. The PCB I used was from Poodle and he designed it to house two trim pots for Q2 and Q3, which gives additional freedom. This would also be the way for me to go.

By now I've realized that I probably should've given more information on what I'm trying to achieve with this.
I don't want this design to be able to recreate an "original" Fuzz Face or Tonebender Sound. I'd like more low-end from both of them. Not woolly mammoth, but think Supa Fuzz or MJM London Fuzz, more that area.
Talking Gain: I've heard many people refer to the MKII gain characteristic as "starting where a Fuzz Face leaves". This might be true to some extent, but the fact remains that the sound of a full blown Fuzz Face and a lower Set MKII aren't the same at all.
And that's why I got the idea for the pot. The approach would then be to design the Q2-Q3 stage according to plan and then add as much boost as wanted. Using separate trim pots to bias both Q2 and Q3 should give enough freedom to make both sounds work.
If you call this a boosted Fuzz Face or a boosted MK1.5 (which would be a MKII) is not my concern.

At the end the result should be a fuzz with an additional boost footswitch.

Talking transistors: Until now I thought I'd use AC128 for all stages, but to be honest I'm not so sure about that anymore...
What I want is to keep the responsiveness to the guitar volume without the boost, which is why I chose to go with AC128 in the first place and use a 50K trimpot to bias Q2 and a 10K trimpot to bias Q3. (Which would be Q1 and Q2 in a Face layout).
Additional question: Since Q1 (boost stage) is only going to be used as boost and not being saturated, the choice here should not have much of an influence, right?

Hi Folks!
So I've been experimenting with a Tonebender/Fuzz Face type of build.
A seemingly common mod to the Tonebender is to add a Switch to jump the Booster stage (Q1), since everything afterwards is basically "just" a Fuzz Face circuit. For those who don't know what I'm talking about:
This explains the mod: http://www.bigtonemusic.com/TBmods.html
For comparison:
Tonebender MKII: http://fuzzcentral.ssguitar.com/mkII.php
Arbiter Fuzz Face: http://fuzzcentral.ssguitar.com/fuzzface.php

First question: The cap in front of Q2 is not polarized in the Tonebender (Film cap), in the Fuzz Face this is the input cap and is polarized (electrolytic cap). By adding the switch and thus bypassing the booster stage in the Tonebender, the non-polarized cap becomes the input cap.
I've already tried this and it seems to work just fine, but somehow my brain is telling me that something's wrong.
The same thing goes for some pedal builders being proud of having replaced every electrolytic cap in the circuit with non-polarized ones to improve the sound. What exactly is up with that?

Second question: My idea is to incorporate said switch into the final version as a footswitch, so I can add/remove boost whenever I want to. But I need some sort of regulation, especially when the Fuzz control is somewhere before noon, the boost just makes it too loud. So I added a third pot right in front of the switch, same configuration as the Volume pot at the end of the circuit (see schematic below).
Any concerns with that? I figured since it's a simple voltage divider it should work, but I'm not too sure about the value. (Though I think with an audio taper the same value as at the end should be a good starting point?)

cheers
Chris