Re: Wiring for strat with aluminium pickguard shield?
Are your Pots floated/isolating on the pickup guard or is the casing touch the current plastic pick guard?
Aluminum pick guard makes a wonderful AM/FM antenna if it doesn't have a solid path to ground -and with Single coil pickups it's even a bigger risk.
If there is not a solid path to ground through the POT casing or a adjacent lock/ring nut touching the casing I would ground the pick guard with a homerun to the 1/4" jack ground lug -to the pot is ok too, but not quite as good if you have a lot of complicated switching.