No other replies yet on your post probably means nobody has experience with these boats. Neither do I. But I am now enjoying my second Nicholson (GRP, this time 48 ft) after haveing a Nic 35. I think all Nics are great, have several friends also sailing them, so if it's the design you worry about, just don't.
I suppose she must have been very well built in her day. I always find that most constructions by C&N show an absolute overkill.
The fact that she is a wooden boat requires a little more caution IMHO.
I would have a specialised survey carried out by someone that knows about wooden boats.
If that comes out ok, I don't think there's much to worry about.