Okay, so I've finished the chest and at first I thought I'd need to rescale it as it didn't seem to sit right. But after referencing some images of the Mark VI I found I was just holding it too low, once in the correct place it looked good.
So I've not moved onto the back and done a fair bit, starting from the spine, moving downwards then upwards. I'm about 40% there and hopefully I can finish it before the weekend.
Pictures to follow.