A car built with a new shell has to get a new VIN number from the DVLA and then pass the SVA.

Points are allocated to the main mechanical parts of the donor and if you use enough you get either an age-related plate or the plate from the donor - DVLA make the decision.

From memory, you need 10 points and the new shell itself is 5, engine, box, brakes, steering and axles from the donor get 1-2 points each.

Stamping the old VIN number into the new shell makes it a ringer - remember that the makers stamps are all in a perfect line and stamped up from below. I tried for ages to get teaps like that, and ended up settling for standard ones.

Use a 2nd hand shell and it's automatically a Q plate.