Looks in great Condition Nick.
I purchased a Ruby kit in December 2017. It is fitted with the later larger bore cylinders, the reverser linkage has been beefed-up to prevent the reverser piston valve being pushed out, and I understand the valve block has been reworked so there is no difference between running forwards or backwards. I did have a problem with the regulator valve being very tight & not fully closing, but replaced that with the regulator valve which came off my Mark I Ragleth having fitted a Train Department replacement regulator valve.
This Ruby will run for approx. 18 mins on one fill of gas, but the gas does outlast the boiler water so I use a water filler valve during the run.
Chris Cairns