Lance, the GSW is a fixed-lens rangefinder camera, not a studio SLR like the GX680.
Anyway, I doubt it's worth the hassle. For a skilled machinist to cobble together some way of mounting the back to the camera, assuming it's feasible at all to get the sensor where the film plane used to be, will probably cost $$$$. OTOH, cannibalizing the lens + helicoid to mount on a technical camera will still require some clever fabrication not just for the mount, but also for an internal linkage to trigger the shutter, which doesn't have an external cable release socket on the barrel. That's also likely to be pricey.
And after all that, you still won't know until you try it whether the lens or, if you go that route, the rangefinder will be up to snuff for the IQ backs, which will be mercilessly revealing of so-so glass or inaccurate focus.
Don't forget the wonky T-setting of the shutter in that lens.
Also don't forget that 65 on 36x48mm will give you a much narrower field of view than the 65 on 56x84mm that you're used to.
EDIT: Just to clarify my point about "so-so" glass, I know that the 65 on the GSW has a fine reputation. But it's sometimes hard to predict which lenses from the film era will hold up well in digital capture, where the optical requirements are somewhat different.