There certainly seem to be some question marks about this car and its lack of history! One interesting feature is that it has been fitted with a second series 2000cc B20 engine (Two single Webber carbs and 3 rocker cover bolts) so would be 80 bhp as opposed to the original engines 70 bhp. It is a pity it has had underseal sprayed all over the underside, this only leads one to think it is a cover-up job!
As to your question Richard to which would be the safer bet this or Richard Thornes B20. I would have thought that the B21 Saloon could be on the road with a good going over, new brakes and clutch, so for say £3-4,000, then you would have a car worth about £25,000. The B20 would cost between £30-40,000 to restore and you would have a car worth £70-80,000. Obviously the B20 is the better financial bet, but would also take a lot longer to do, and the whole project would take much more time plus financial comitment.