I'm not super familliar with TVR, but even so I even less of the 500. I do have some articles about them, but the 400 doesn't get very prominent mention. I know the 200 and 400 are the sort of Tuscan style. Are the 500's a wedge design like the 350i? or curvy like the Cerbera? I think they run the the 5.0 liter Rover motor, but somewhere in around there TVR started using it's own 4.2 to 4.5 liter motor, but probably not in those.
I do know that the cars are supposed to be outstanding, in that TVR has come a long way and is finally playing with the big boys with chassis design and suspension, something that they had problems with for years. Quality control was supposed to be good as well ( bear in mind it's still not a Honda )
Can't offer more I'm afraid, but good luck with it. You certainly won't see another one coming the other way very often!