Holden 308 should not have any overheating
Problems at all , unless you have some major problem like head gasket or a crack.

Mine has factory ac and power steering in my wb panelvan and on the hottest day stays between 1/4 and 1/2 no drama , but
There's a reason why .
It has a custom made fan shroud and twin thermo fans and I run a 140 amp alternater.