Last time I saw it, maybe 6 months ago, they were waiting for the pistons to come back from a firm (they were well down the list of the firm). Then the front end needs to be set up etc. etc.
They had previously lifted it 10+ times trying to sort out the misaligned axle boxes/horn cheeks (now sorted), then it was found the engine wasn't weighted enough over the trailing truck (more lifting but all corrected). But with such a small workforce and the Zephyr/scrapping of items taking most of their time the R's progress is slow but continuing.