You should probably start on a slightly damaged Silvia, with mild panel damage, maybe a pushed-in radiator support. This way parts are cheap and it wouldn't be too hard to fix.
Even then, you would at least need to know how to weld. Trust me, having fixed two damaged cars already, it's never worth it in the end.
Unless you can get all the parts you need cheap or free, then don't bother with expensive cars, or it will prove to be a very expensive lesson.
I'm on my third repair now and just can't be bothered. Alligning guards, bonnets, cutting, straightening, it's just a pain. Hence, I've just taken my car to the panel beaters this time.
With regards to switching plates, it's not that easy. If the car was declared a write-off, it will need to get a VIV certificate before it can be re-registered. They are used to dealing with all the Habib's from Broady, so they know exactly what to look for. They thoroughly check that the numbers are legitimate and not swapped over, ensure you have receipts for parts and that panel work was actually completed.
Anyway, good look with your endeavours.