As a very satisfied customer of the first KMCE wagons, I can thoroughly recommend them. Despite their archaic appearance, vehicles such as this were commonplace well into the 1950s, thus the "A" class era, though they were beginning to get thin on the ground about then. Some lasted until the very early 1960s, at which time despite Inchicore building new wagons at a serious rate, 80-year-old goods vehicles could still be seen. More than a few may be seen in photos of the West Cork system in 1960/1, and I have seen very late 50s pictures of vehicles of this era in many other places. I particularly recall seeing a very old van at Adare many years ago, and others (GN / NCC origin) in Belfast in the 1960s.
So these are suitable for an GSR or CIE layout as well as pre-1925, and many survived to become clad in flying snails.
Last of the very ancient stock in actual service was probably about 1963/4, so a 121 or at an absolute stretch maybe a 141 could have hauled one amongst newer wagons and recently acquired ex-GNR stock.