http://www.ripsracing.com/index2.html
Their email address and phone numbers are on the site. - bonus being that the exchange rate is currently 1 pound = 2.80 NZD.
They also have a fair few customers from the UK that are running big numbers.
if you are not after power the 2860-7's (similar to N1 turbos and the HKS GT-SS kit) are probably your best bet if you want to push them they are capable of ~320kw the 2860-5's (similar to HKS 2530's) are more of a 350-370kw setup.
Ash, your car is RWD isnt it? just throw the 26 head on a 30 bottom end with a set of -5's. It should be just as responsive as the 26 with the -7's and it would be hard to spot the difference between the two engines once in the engine bay.
its already been done. from memory they did the whole conversion for $1000 you need to use the R32 RB25DE head if you want it to be a cheap bolt off bolt on affair. the R33 head will require modification to work.