Thanks for the share and super excellent job both inside and out..
I will try to answer a few questions you had: My suggestion is to use a fatter cap for the Strat (100n) and for the Les Paul a (22n) for a tight tone then this switch simply becomes a very useful Strat (single coil – P90) switch on one side and a Les Paul (Humbucker) switch for the other side with no EQ twiddling. Finally I suggest using the circuit at the Lowest Gain settings for excellent smooth sustaining Fuzz tone with excellent clean-up potential and leave the (Full-Up) setting for very low or “Vintage” output guitars.
So the result would be with the switch in one position you would have 22n which is nice and tight for the Les Paul and in the other position roughly 122n for allowing just enough more Bass through for the Strat but still tight. (see image). If the 2nd Cap choice is higher then you will simply add additional Bass Pass through Frequency to the math.
I hope that helps as I have been using this circuit for 8+ years now and remains one of my favorites whether it is the Hot Chilicon of Old or the New SRIRACHA FUZZ of today.