Hi, you should reply to your first topic if you want to add more pics or info rather than keep starting new topics, that way we can keep all your info in one place. I will sort them into one as soon as I am back on my pc.
It looks like you have a project on your hands there! To be honest, the tyre sizes are the last things on your list at the moment! The wheels and tyres can be done at any time, keep it on the donor wheels at least until it is painted.
Looks like you have most of the parts, do you have a rear light panel or the front light housings? The pile of bits are things like the scuttle panel, interior rear window finishers, under bonnet trim, drip strips for the boot etc.
How much work is involved depends on how well it has been put together so far. Things like how well the roof has been bonded in place, if the welding has been done well and if bits have been bonded in the right place. The gaps are something you have to work on even if everything is put on correctly, so don't worry if they are a little out, its the alignment from one panel to the next that is most important.
If you do it yourself it could be a nice car and wouldn't cost you too much. To be honest if you pay a builder to do this you would be unlikely to get your money back on resale.
Good news is there are plenty of builders on here and build diaries to help ou get it done. Just ask if you get stuck!
Do you have a build DVD for it?
If you are missing parts extreme should be able to sort you out with what you need.