Amazing build, this thread entertained me for the last hour. Thanks for the abundance of pictures you provided too! I'd never seen pictures of the dual fuel system taken apart before. In a lot of ways my 80 in Aus has more in common with this GCC spec than typical US spec models (barn doors, dual fuel, part time TC, etc), but it was still interesting to see the differences between the two.
Out of curiosity, am I right in saying your 80 has central locking, with the barn door centrally locked too? That's not a very common setup I believe. I'm retro-fitting central locking to mine, and tracking down the power actuator for the barn door took some doing. I don't think it was ever offered here. It seems the higher spec models that came with central locking generally also used the lift-up tailgate. I prefer the barn doors myself. They're more practical, even if you do need to cover them half up with a rear tyre carrier to stop them looking funny.