I'm not 100% sure tbh but I know you will get some wiring with the head unit included, ...just not sure that it's called the "patch lead". It's usually wiring with specific plugs to suit the make of head unit.
Lots of patch leads here: https://www.dynamicsounds.co.uk/stereo-patch-leads.html
See if anyone else replies on here or check with the audio place you get to fit it if that's the way you are going.
You could also try asking Buster directly as he seems to know the 350's ICE set ups pretty well. He is here: http://www.350z-uk.com/user/11228-buster/
Also this "volume fix" is worth a read: http://www.350z-uk.com/topic/107583-how-to-busters-rca-headunit-volume-fix-guide/