S7 is labeled "GR Disable" I would think that would do it. The bypass switch on a real 1176 is incorporated into the attack pot. If you compare the old schematic and trace the attack pot wiring to the two big caps, the pot disconnects them from ground, if you look at the "GR disable" switch, Im guessing, but it should probably go to the same spot and that should bypass the limiter function and just give you the line amp output.
hope this helps.
dave