What info do you need?
It's a kit! As Neal said, similar to others produced at the time. The chassis is very solid, front uprights etc are Holden HQ, usually set up for a Renault trans (these are a good option provided you drive it sensibly), the body is average. The end result is more a function of the dedication of the builder than the origins of the kit.
The figure that is often bandied around for GT40NZ production is 34. It is my impression that probably half of them are still languishing in sheds around NZ currently uncompleted. There are several in the States, Kevin owns one in Oz and is a very helpful fellow, and as well as him and Neal, there are several other GT40NZ owners on this site. Steve (sp250), also on this site, at one stage worked for Dave Harvey the owner of GT40NZ after Phil Ware.
So if you do pull the trigger on this one you should have no problems, this site is a great resource and there is not much GT40 related info that is not available in the archives or for GT40NZ specifics directly from guys like Kevin, Neal or Steve.
Good luck with it!