Ok I'm one of the more experienced in CA18 installs into 1200s.

The conversion is best done on an Automatic gearbox equipped Datto, because of the bigger trans tunnel.

Buy the engine front cut ($2500)
If It's a Ute, Get R30 Skyline Stumpy gearbox ($500),
Get bigger brakes ($500-$800)
Convert to Hydraulic clutch ($100) Requires custom mods (not bolt-on)
Custom Engine, Gearbox Mounts ($200-$400)
New Timing Belt ($100)
Bigger Radiator ($300)
Custom tailshaft ($250)
Bigger Ute Diff ($300)
Custom hosing for radiator and intercooler ($200)
Custom Exhaust ($400-$900)
Engineer Certificate ($300-$450)
Wiring (someone else doing it) ($500)
Fuel pump hosing filters,return line, surge tank ($400-$1000)
Engine Oil, Gearbox Oil, Coolant, filter ($100)

So base cost would be $6650. Max projected cost $8900.

This is not all including labour which should be estimated at probably 5 x 8 hour man days.
$50 / hour Add another $2000-2500 for skilled labour.

So $8650 -> $11,400.

This is for a stock installation. If you wanted a bigger turbo add $2500 (including manifold and gaskets). Then you need bigger brakes and diff $1200. You'd also need a bigger clutch $500. Bigger front mount intercooler $700.

So for a fast 1200-CA18DET install, expect up to AU$16,400 on top of the purchase price of the Datsun $1000-$4000.

These are realistic prices. Don't fool yourself by looking at engine price alone.

Chris.