Best of luck with your staghunt, they are an awesome animal to hunt during the roar.
And a double is the ideal rifle! just make sure you oil it well, it can be pretty wet here in NZ.

These guys both offer honest free range opportunities for wild reds on the South island
http://flyfishhunt.co.nz/
and
http://www.hawea-hunting.co.nz/

a Wild NZ stag does not have 18+ points and won't score anywhere in the SCI books.
you should expect a 12pointer if you are after a true wild deer, but in saying that there is nothing wrong with a 400+ SCI.

Regards
H