I don't want to offend them by asking too low, but I will reference '350z owners who are more knowledgeable than me' and say they suggested 9k, with the intention of hopefully meeting them in the middle at £10.5k.
Looking at other old Japanese cars it seems that low mileage examples seem to go for a lot more than the high mileage ones so that's why I thought the price was reasonable, but I guess quite a few people disagree haha. It is 5 and a half hours away so if I go to look at it I feel like I'm pretty much committing to the purchase. I will try to ask the owner what I can about the really good points everyone here has made!
I have to say from what I can gather it seems like a really good and clean example, and hopefully if I look after it I might even see a little appreciation with the exploding JDM car market. Maybe it'll help to cover the cost of insurance
But thanks to everyone for your help I wasn't expecting this many responses!