There was one set of these old veterans (in black'n'tan) used for summer excursions as late as 1974, after which I think they were withdrawn. One of them was ex-GSWR 1287, currently in use as staff room / operating manager's office at Downpatrick. This last set was based in Dublin. The black and white photo is of these. The colour photo was taken on the 1964 all-Ireland joint LCGB / SLS / IRRS steam tour. The coach shown is a former GSWR dining car; the rest of this train was composed of laminates.
Until the mid 60s, wooden coaches were occasionally to be seen in main line trains. While no passenger carrying six-wheelers were ever repainted into black and tan, at least two ex-GSW six wheel passenger brake vans were; one even had gangways fitted. This coach, GSWR 69, is now also at Downpatrick undergoing a gradual rebuild into a more traditional pattern, but reincarnated as a brake first.
The dining car shown in the second pic was still at work in the late 60s.
On a model layout, accuracy would be represented best by a single wooden coach in a set of laminates / Bredins (though probably not Cravens); or if it was based in the greater Dublin area, or that of a fictitious large city (!), maybe a rake on excursion work. If it's mid 60s, there could be one still in green.....
I'll stop dreaming now; the cat has to be fed!