Thank you both John and Simon for your views on aircooled Porsches, very interesting, but along with Ferrari, not a make I have ever seriously considered for various reasons.
With the way that current cars are taxed and with such high depreciation, I am seriously wondering if it is worth considering running a 40 + year old car. There are quite a lot of very usable cars around now, some still at comparatively low prices, Scimitars for example and maybe with a little restmodding, they can be made quite civilised and cheap to run. Just thinking out loud obviously.