Or you can buy one of these and fit it too your top radiator hose, and put the sensor in it then just lengthen the wire.
https://www.supercheapauto.com.au/p/saas-water-temperature-gauge-adapter---aluminium-34mm-radiator-hose/525639.html
Yes that is the connector.
This is what you need.
https://www.ebay.com.au/itm/TRIDON-water-temperature-sensor-TTS064-fits-Holden-Commodore-VS-3-8-i-V6-more/223612366754?fits=Plat_Gen%3AVS&epid=20017005324&hash=item341055efa2:g:QsQAAOSwy0Vfc3HL
Go to a engine rebuilder and ask if you can hire their engine oil pressure primer tank or make your own, I made my own out of PVC pipe and brass fittings worked like a charm.
https://www.specautoequip.com.au/service-equipment/engine-oil-pressure-primer-tank
Series 1
https://www.ebay.com.au/itm/Genuine-Holden-New-Front-Door-Check-Link-Suits-VT-Commodore-Series-1-only/174013449648?epid=22021176696&hash=item28840285b0:g:~kgAAOSwTYJdaL2u
Series 2...
If it's a V8 you will need the ELM327 if it's a V6 you will need a ALDL cable, checkout the link below.
https://forums.justcommodores.com.au/forums/envyous-customs.251/
Yeah it's that easy just buy a flashed vy l67 PCM from mace, after you receive it send your old one back for a $50 refund, then extend the necessary wires and your done.
Why would you run a 10psi pulley on a intercooled set up, maybe fit a 14 or 16 psi pulley, to answer the question yes a l67 with some basic mods will beat vz sv6.