As much as i'd love to own an N/A version to add to the collection, theres no way in hell i can...I know stating "believed to be" adds to the mystery but I'd want some proof of nismo originality (more than an engraving on a strut tower).
Irrespective of any Nismo heritage, (and there is no identification other than the random number stamped into the strut tower), I doubt it will make any difference to the perceived value of the car, it's a K11 at the end of the day and it's been proven time & time again that they are not marketable.
Anyway, the story goes that 4 of these were built for a bunch of rich Japanese businessmen in the mid 90's as a ready to go race package. The engines were, at the time, Nismo N1 spec I guess and came with a lot of spares support, many of which are still with the car. This one has almost enough parts to build up another complete engine and has 13 sets of camshafts to name a few. I was not able to trace anything specific such as heritage though when I was interested in it back in 2007 I think it was......
Allegedly the reason this one originally came up for sale, was due to one of the 4 original owners selling up and since they all used to race together as a group they gradually lost interest and came up for sale over time. This one ended up in NZ but never really got used, then made it's way over here, never really got used and so on....
Being in the process of a serious N/A build, I can tell you that anything needing to be replaced on this car will have to be pretty much bespoke which is going to cause plenty of wallet pain and given that it's not road legal it limits the field to racers only. Given the current market, availability of other cars I doubt this would fit anywhere, so would perhaps be purely down to extravagance.
The above has very little credibility other than being a nice story. As people have said already, I hope it finds a good eccentric owner. It's certainly a car I wouldn't mind doing a little tag-teaming with