I'm going to give you the point as you describe fully in your last post what I have this car as.
However, I haven't found one site which describes the car as you say it is, yet it appears on numerous sites as the 1963 1800GT prototype. I actually got the picture from a Swedish Volvo club site, but the same picture (I've never seen another one) appears on quite a number of other sites with the same description.
Although you could say those wheels look to be later than 1963 that isn't necessarily true. There were alloy wheels of similar appearance appearing on cars around that ime (look at Abarths for instance) and they could well be from 1963.
So this is solved and I'm describing it as what you've said I think it is; if you can prove definitively otherwise (any links please PM as you can't post them within the puzzle) then I'll gladly change the heading. But I think this is in fact what it is.