If you're not worried about getting it homologated for circuit racing and only want to do drags, you only need a 5 point half-cage. Good for up to 10.00 sec.
Seeing you're Auckland based (Meremere), NZDRA does not apply as they adhere to IHRA rules. Go to section 3.61 and you can see the diagram they provide.
You will also need an SFI approved crank pulley, fixed back seat, harness bar and harnesses, shield plate over top of the transmission in case of flywheel exploding, drip tray underneath engine, etc. List goes on.
Worth talking to an IHRA tech inspector before you start.