You need a DPDT at least if you want to bypass an effect: The best you can get with a SPDT is to have the guitar feed both the fuzz input AND the lug 3 of the SPDT, send the fuzz output to lug 1, take the output to the amplifier from the common/lug 2 as suggested above. However, in "bypass", the guitar signal will still be connected to input to the fuzz circuit and this can cause unwanted effects.
Using a DPDT, the simplest bypass (with no LED):
or any of these use a 3PDT if you want an led:http://www.aronnelson.com/gallery/main. ... alNumber=2