All depends what someone is willing to pay, it looks like a mint shell with potential. It would look better as a sleeper with pov spec bumpers. You could probably advertise it at £500 fixed or not fixed and get that easily. The HG failure is something people would ask about, as in how badly has it gone? That will effect the price people will pay.
You could advertise it for more, say £700 because of the shell, but whether you get that or not is a different story.
How much would you realistically want for it? That's the question