All three of these sales are currently live on UK ebay.
This beautiful little '40s NSU engine and box has to be worth £1000 ? Rather strangely listed under Collectables which is probably why it hasnt sold. Buy it here
Plunger Tiger Cub heap of the week, currently at £500. I once did a lot of miles on the back of one of these things while my bike was off the road, it was not a great experience. Details say "worth £3,500 when restored". is this the same £3,500 that will buy you a perfectly good Ironhead Sportster, T140, Z1000 etc. Do everyone a favour and push it back in the shed for another 37 years.
You can do some good things with air cooled Zs, this is not one of them.