Mike,
I have the Bosch knock sensors mounted on the 993 bridges same as shown in Craig's photos. I did not move them around to replicate your scenario (sensor on throttle console), so I tried tapping at the console to see how the sensor responded. Not exactly what you're looking for, but somewhat relevant.
[sensor on 993 bridge; tapped throttle console]
[sensor on 993 bridge; tapped inside exhaust port]
I was simulating knock by dropping a small ratchet extension onto the throttle console and tapping inside the exhaust port, so no way is the energy applied consistent. Consequently I wouldn't read too much into the signal strength. I think it is significant that the signal is similar (frequency and damping).
Conclusion? It appears the signal propagates across the block. I even tried the same experiment using the sensor on the opposite bank and got similar results. I suspect the ability to detect knock is going to come down to the ECUs capability to detect and analyze the knock's acoustic signature in a sea of noisy mechanicals (like the valve train, as noted above). Part of the tuning is setting the characteristic knock frequency based on the cylinder diameter (D):
Knock frequency (kHz) = 1800/(Pi * D)
I'm going to use the ECUMaster EMU Black ECU. Version 3 of the firmware (now in beta testing) is claimed to be able to attribute knock to a specific cylinder (by knowing where each piston is in its cycle when knock is detected) and respond on a per-cylinder basis. We'll see.
Steve