If you bring it over to me in SE London I will have a look at the bodywork for you (guess you can only do that once the overheating issue is sorted). I think that any sensible restoration business would need to have a look in the flesh before they will get down to the nitty gritty of actual cost - photos are really only a very vague indication. I have a couple of vans here mid restoration so you can see the sort of thing that may have to be done.
Cheers
Jules
RatSport www.ratsport.co.uk