Rather have a 3k GT? Something special about owning a low mileage GT though. I had mine from early 30k's as long as you plan on keeping her. The red clover 170 looks like an end of line car too. And that plate is worth a bit.
This is the thing, an untouched blank canvas low mileage car for 10k is ok i think. It shows our cars are holding their money. I also feel as strange as it sounds especially in the economic climate where diesels are getting a bashing, these cars are becoming more desirable, as people start to realise their potential when properly and correctly modified. Especially the models with the larger injectors and up rated fuel pumps ripe for tuning. I came from modified Audi TT's and honestly i can say i love my modified clover much more as a fast road car, the way she communicates back to me, and as a track car too. The haldex quattro on the TT used to drive me bonkers, you could never truly feel what the bloody chassis was really doing on the limit. My clover just digs in for grip and is more forgiving and intuitive on the limit.
it comes down to the difference between worth and value....your car is ''worth'' more than mine in monetary terms but i would argue as a ''possession'' they have similar value to us as owners, performance is similar although i would be the first to admit your's edges it as you have taken considerable time effort and money to get the perfect car, I have not gone to quite the same lengths..but mine is a peach no doubt compared to most.
my problem with going really low mileage is the only thing you gain is monetary value which as the car gets older and you put more miles on it of course is diminished..I would rather the car have already suffered the depreciation when i get it provided everything is mechanically sound and the bodywork is good. the figure to do what we have done is the same whether the car is an 07 with 100k on the clock or a 10 plate with 25k on the clock. doing it on the £3k older car saves you some where around 6-7k in total.
so its simple, spend 10k on the car and then another 5 sorting it or 3k on the car and another 5k sorting it....I think 5k for a newer number plate a lower reading on the odometer and some bigger injectors and higher pressure pump is bloody steep! and given some standard cars are now making 260 bhp on the Autolusso hybrid set up I don't see the point.
a final point, a fiat /alfa tech I trust told the service life of the JTDm engine is 300k! on that basis the engine mileage is not a huge consideration provided the bits around it are wearing well..
that said you know I think your car is epic and likely the best one in the country, the money you have spent would not have made sense on a cheaper car and you required what you bought to achieve your aims...you wanted perfect and that is what you have, and i have to respect that.