It doesn't matter which pin you use (12v or 5v) as long as your resistor value is correct.
To be honest I've never trusted ANY of the resistor values on ANY of the accredited Amiga->SCART diagrams.
Most diagrams recommend connecting pin 8 to 12v via 1K ohm resistor in-series. How on earth that makes a voltage of between 9.5v and 12v I dunno.
Most diagrams recommend connecting pin 6 to 12v via a 150 ohms in-series. How on earth that can make the voltage between 1-3v, especially as it uses a lower resistor value to that above!!
If anything I would have thought the resistor values are the wrong way round!?!
