So we started the tidy up and ... things may look to have gotten out of hand. Don't worry we'll have all this sorted out in no time.
The good news is that the windows now all work - which is particularly pleasing because that's one better than when we bought the car. It also looks like the mirrors will be easier than expected and we now think using the original dash is the better option because heater controls and dash vents will work without fettling and, yeah, it will actually fit in the space we have - won't be as cool though...
The bad news is that we've made a huge mess of the interior and run out of crimps. I thought that 100 would be plenty, but no, our rate of wastage has been staggering... There's nothing for it though, I'll just have to wear it and order some more (should be OK at slightly less than eight cents each).