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its a fair job to turbo something that was never ment to be turboed.
to start off with the static compression ratio im guessing will be quite high so you would want to run some lower comp pistons, proberly some forged alloy ones as well to cope with the added heat from a charged intake.
Fuel system needs to be able to cope with rising air flow so you will need bigger injectors and most likely a better than standard fuel pump.
a descent head gasket is a good idea, not sure if holdens have much in the range of multi layer steel or even copper hea gaskets but they would be ideal over a standard graphite style.
new set of head bolts or some head studs if avaiable to keep the head down.
then you got your cam and head gear, your going to have a charged intake now so you want the valves to open up a fair bit to allow as much air in with out restriction, so either a different camshaft with increased lift and duration or some different ratio rockers to open the valves further but ideally you would want more duration as well.
The aftermarket rockers would increase valve speed while opening the valves further so valve seats would suffer over time, plus you would want some descent valve springs.
if the standard head doesnt flow very well under boost then might help to do a radious cut on the seats and port them in and ex out slightly to increase flow capacity.
not sure what the standard chambers look like but im guessing there not ment for much turbulence so some chamber manipulation would be good.
open up your intake with a descent sized t/b.
one of those mace engineering spacers on the plenum would be a good idea as well.
IMO i wouldnt be turboing a 300,000km old n/a i would be stripping it down before running 10psi on it.
also are you only single turboing it or twin?
single turboare you only single turboing it or twin