Got your PM shadowcastaz- according to this schematic:
http://www.gibson.com/Files/schematics/S1series1.pdf ...that "bypass switch" is a 3PDT toggle (meaning three switches ganged together, each with two positions - dual throw). Its an "on-on" config from the look if it (i.e. it has two fixed positions). In that technical specs pamphlet that John posted, however, they talk about that switch having a center position
. That confuses me - maybe someone with an S-1 can verify. They might have reused/rigged-up a pickup selector switch there, or something.
In any case... going strictly by that schematic, a 3PDT switch with *two* positions (no center position) would do the trick.
I found one full-size toggle with that config here:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=CKN1498-NDThat one has a big round switch bat on it and mounts in a 15/32" hole (outwardly full size, although the switch housing itself looks "mini"). That should look right - maybe it'll work for ya.
That S-1 body is lookin' good, BTW!