waddle, as has been discussed here many times, shell swapping is illegal, unless you mean a new Heritage shell. Have you seen the price of those lately? Not worth it for a City E, surely?
The thing to bear in mind is that the MOT rust test is basically useless as it fails miserably to deal with some serious issues outside of the "prescribed areas", but, more annoyingly in this case, does not actually state where the problems actually lie.
We nay infer that this is going to be a floor/sills/inner wings/heelboard/Rear subframe job at least, but without seeing the car it is impossible to be more specific. But as it has apparently been patched for years to scrape through successive MOT tests the situation may not be good.
I would seriously suggest selling it to someone who has the capability to restore it properly.End of the day, the model is somewhat irrelevant now days.. a mini is a mini to most - it could be rebuilt as absolutely anything the op wishes!
As I understand it, re-shelling can be somewhat of a grey area? Although.. whilst I will not recommend it as I'm by no means in a position to do so.. it is VERY common and has revived many, many minis over time - people will use the original log book , swap the id plates over and build it back up. as long as its a shell of the same mark and roughly year.. whats different to that and replacing just about every panel as with large restos? an entire new shell is even more un-original!
Whilst It's up to the individual what he/she chooses to do with ones own car,
Seeing as this is a public forum, it is very unwise to encourage people to do something that could result in their pride and joy ending up worthless on a Q plate,
the legalities of Reshelling has been debated over and over,