Brief update, I called round to Garrard & Flack, where Ed kindly cut a few inches off the end of one of my clefts. He has a moisture meter with long prongs, so we compared the middle and the outside edges. Interesting, the outside is currently about 12% moisture, but the middle was over 30%.
So, in terms of overall density, my calculations are pretty accurate. What is clear though is that there is a lot of water that still needs to shift outwards. So, the wood is back in the rafters, and will stay there for a few months yet.