Correct. For anyone modelling a green CIE steam loco, 800 is in absolutely standard CIE green, lined accordingly. However the “G S” on the tender is wrong for this livery, as in that green they only ever had the flying snail.
Regarding 803 and 804, thete were rumours at the time of these being planned, and tentatively named “Deirdre”” and “Grainné” (not Aoife, though). However, both official sources and memory of people who would have been involved, e.g. my grandfather, fail to show any hard evidence of this.
At the very least, though, there was likely to have been talk of it in high places, as well as of the large 820 class tank engines which got to the drawing board but no further.