Hi Timbo,
Your right, they are the bits left over from Scimitar 2 conversions, there were more CVRT Scimitar Rolling Hulls in Withams yard today, they are not restricted items, they are for sale for scrap metal sort of money, had a good look at a Scimitar they had just sold, No Turret, No engine, Not much else, only a hull and road wheels.
I think it would be very hard job to put one back on the road, might be possible if you could swap the bits from a Sabre into one?