Originally Posted by IainRS1700T

On that last bit, your emissions would be relevant to the age of the plate. So if you went for a specific doner car, and re-shelled it, it could remain on the original plate subject to an inspection and your emissions would be relevant to the age of the engine (or original reg) I think. ie post '92 would mean a cat is required. If you Q'd it, (ie used shell and used parts) it would be tested on emissions for the age of the engine once again. If you went the 'new' route with all your parts, to go for a current plate ('61) then it would be tested on emissions regs for the current law, ie like any new car with cat required etc.
Cheers
Iain