The Austerity I am leaving for DJModels to do, and as the 50550 is very close in design, it might appeal to Dave to do it.
The 16" is a bit of a uniques story, as I will be doing it in OO and HO, due to the only standard gauge Hunslet 0-6-0ST (PWD79 'Plum') in Australia being a 16" at the NSW Rail Transport Museum, and is easy for me, as a volunteer, to access. Same with the Mersey Tank