that's a shame
if it's a "write off" could you buy it back from the insurance and then have the work done yourself?
also, I don't know of any "GTD" finished cars that had an intercooler AND no turbo water pump ...
You say the engine is not the original one, maybe check and see if it's not a "JR" instead of a "RA"
That was never the problem. The insurance didnt take it. The assessor classified it as being economically irrepairable, but the car was repaired anyway on the cheap but because the assessor wasnt involved, he wouldnt unblock the registration certificate. No amount of money would change that.
As for the engine, maybe it wasnt a proper GTD engine, but it worked one way or another. I never did get the engine number off it in the end, so I suppose that remains a mystery.