Do NOT!! put anything other then a VZ Kit onto your VZ. It will look ****, and you will be ridiculed.
Also, if you change the kit to say a Clubby/SS/Calias.. You will also have to change the taillights.
And if you want to put a VY kit on your VZ, you will also need to change the bonnet and headlights (not worth it).
the vz hsv kit would be the way to go, the vz and vy bonnet are the same item, so if you did end up putting a vy front bar on, all you would have is to change is the headlights
as to a rear bar, there are two types of different length taillights fot the vy and vz commodores
berlinas, calias and hsv's use the longer type
all the other models use the shorter tail lights including ss commodores
there are aftermarket rear bumpers made to suit both length tail lights if you look around, so you dont have to change the tail lights if you dont want too
were you looking for someone to supply the kit, fit paint etc?